Kevin McCarthy and author Jack Finney have always denied the rumor that the story is a statement against McCarthyism and Communism; they just saw it as a thriller. Director Don Siegel, however, believes that the political references to Sen. Joseph McCarthy and totalitarianism are inescapable, even though he tried not to emphasize them.

During its original release, papier-mâché pods were on display in theater lobbies, as well as black-and-white cutouts of Kevin McCarthy and Dana Wynter running frantically away from a crowd of pod people.

In 1994 this film was selected for preservation in the United States National Film Registry by The Library of Congress as being "culturally, historically, or aesthetically significant."

The film was almost called "The Body Snatchers" after Jack Finney's serial, but it sounded too similar to the Val Lewton film The Body Snatcher (1945). After several such titles as "They Come from Another World", "Better Off Dead", "Sleep No More", "Evil in the Night" and "World in Danger", the studio finally settled on "Invasion of the Body Snatchers".

During test screenings, much of the film's original humor and humanity was cut when the audience found it difficult to follow and laughed at all the wrong moments. The studio insisted on edits because it wasn't policy to mix humor with horror.

Filmed in 19 days. The cast and crew worked six days a week with Sundays off. The production went over schedule by three days because of night-for-night shoots that director Don Siegel wanted.

Production Designer Ted Haworth came up with a fairly simple and inexpensive (about $30,000 total) idea for creating the pods. The most difficult part was when the pods burst open, revealing the likenesses of the actors. The actors had to have naked impressions of themselves made out of thin, skin-tight latex. Making the casts, which involved being submerged in the very hot casting material with only a straw in their mouths to breathe through, was grueling for the actors, especially Carolyn Jones, who was claustrophobic. Dana Wynter recalled, "I was in this thing while it hardened, and of course it got rather warm! I was breathing through straws or something quite bizarre, and the rest of me was encased, it was like a sarcophagus. The guys who were making it tapped on the back of the thing and said, 'Dana, listen, we won't be long, we're just off for lunch [laughs]!' In the end, we had to be covered except for just the nostrils and I think a little aperture for the mouth."

Producer Walter Wanger wanted a Winston Churchill quotation as a preface, with Orson Welles doing the narration. When they couldn't persuade Welles, Wanger tried to enlist science-fiction author Ray Bradbury. He declined as well.

Sam Peckinpah, who has a small role in the film as a meter reader, also worked on the movie as a dialogue coach. He performed the same job on Don Siegel's other films of the 1950s.

Universal's UK DVD (824 346 1.11) comes with a choice of the original black and white or a colorized version. The black & white's running time is 1hr and 20 mins while the color version has an added five minutes to its running time.

Screenwriter Daniel Mainwaring had brushes with Hollywood "Red Scare" witch-hunts, which lends credence to the theory that the film is subtle statement against McCarthyism. Dana Wynter agreed with that sentiment, although she didn't recall the mention of any political statements on-set. Kevin McCarthy believed the film to be an attack on "Madison Avenue" attitudes. Director Don Siegel joked that the pods represented movie industry executives.

The last sequence was shot, not on the actual Hollywood Freeway, but on a little used cross-bridge. The cars were driven by stunt drivers. Don Siegel said later that Kevin McCarthy was in real danger of getting hit, because the sequence was shot at dawn and he was near complete exhaustion.

Kevin McCarthy didn't particularly like the script because he felt that, in streamlining the novel for the screen, depth of character was lost. He thought it was a mistake that these fairly sophisticated, educated characters had such bland dialogue and manner of relating to one another, "lacking the curves and nuances that you often hear in the conversation of ordinary, mature men and women."

The film's action required leading man Kevin McCarthy to run for days on end. In numerous scenes, his character sprints for dear life over every possible terrain. "I got charleyhorses [cramps]," admitted McCarthy. Just before the film draws to a close, Dr. Bennell runs through traffic in a panicked frenzy, screaming "They're here already! You're next! You're next!" Since the exhausted actor hadn't been sleeping well, Don Siegel told his stunt drivers to remain extra alert in case McCarthy tripped without warning. "I was terrified that his timing would be off and he might fall down under the wheel of the cars and trucks," Siegel admitted.

Ranked #9 on the American Film Institute's list of the 10 greatest films in the genre "Sci-Fi" in June 2008.

Kevin McCarthy would later reprise his role of Dr. Miles J. Bennell in the remake Invasion of the Body Snatchers (1978) and Looney Tunes: Back in Action (2003).

The tunnel scene where the hero hides briefly from the townspeople was filmed at Bronson Cave in Griffith Park, famous with locals as the Bat Cave.

Don Siegel later claimed that during filming he crept into Dana Wynter's house and slipped a pod under her bed, causing her to become hysterical when she found it. "That is a bit far-out," Wynter replied when she heard Siegel's account. "Actually, he left it on my doorstep. He had a girlfriend who lived next door to me . . . and he would pass my cottage all the time. And one night he just left it on the doorstep!"

Throughout the years, Sam Peckinpah (who appears briefly in the film as the meter reader) claimed that he had done work on the script ranging from modifications to major overhauls. Those who worked on the film claimed that if Peckinpah had made any changes to the script, it was limited to a few lines of dialog. Peckinpah's claims became so inflated that the actual writer, Daniel Mainwaring, threatened to file an official complaint with the Writers Guild of America, so Peckinpah backed down. When Peckinpah died in 1984, many of his obituaries still carried the claim that he had rewritten the screenplay for this film.

The biggest problem director Don Siegel and company had with the studio was over the use of humor. He, writer Daniel Mainwaring and producer Walter Wanger had scripted scenes with humor in them, and Kevin McCarthy said the actors improvised some during shooting. When the film was still in the work print stage, Siegel and Wanger decided to try it out in front of a preview audience behind the studio's back. Much of the humor was still in the film at that point, and the audience response went from shrieks to screams to laughter and back again. Siegel had sneaked a tape recorder into the theater so they could prove to the studio just how great the reception was to their rough cut. However, Allied Artists head Steve Broidy hit the roof when he found out and wanted to know why the audience was laughing in places. He ordered any trace of humor removed.

The scene in which Miles and Becky are pursued up a long, steep outdoor staircase was shot in Bronson Canyon in the Hollywood Hills. The head grip came up with the idea to build a small dolly with wheels that rode the top of the staircase's iron rails ahead of the actors.

In the decades since the film's release, the term "pod people," which was inspired by the transformed characters in the film, has become a popular phrase signifying people who are emotionally and creatively dead.

Dana Wynter genuinely enjoyed the shoot and noted that everyone in the cast and crew was extremely nice to her as a newcomer--except Carolyn Jones. She said the more experienced Jones was "strangely unfriendly and unhelpful," yet Wynter still managed to hone her style by observing her.

The pace of the shooting meant there was little time for the actors to rest between takes of the exhausting chase sequences. And there was no time to discuss scenes. Dana Wynter said the actors were always responsible for mentally rehearsing their characters and actions before jumping in front of the cameras.

Only $15,000 of the budget was spent on special effects.

Production Designer Ted Haworth was worried that studio executives would object to the "nudity" of the pod likenesses. Don Siegel reminded him that Hollywood executives were all pods and, as such, had no real feeling about anything, including nudity. One executive, however, voiced strong objections and ordered Siegel to eliminate any nudity from the picture. Siegel returned to Haworth and told him to continue as planned. "I was sure that before the impressions were made, this executive would have become a pod, too," he said in his autobiography. At any rate, the issue was fairly moot; the pod replicas are revealed under foaming soap bubbles that manage to keep any overt nudity concealed.

Becky and Miles paraphrase William Shakespeare twice. "I know a bank whereon the wild thyme blows, Where oxlips and the nodding violet grows" is from "A Midsummer Night's Dream". "That way madness lies" is from "King Lear".

Even though the film was "produced in Superscope"--according to the opening credits--and released in the 2.00:1 aspect ratio, it was actually shot with the spherical 1.85:1 aspect ratio in mind. The scope prints were created in the lab in post-production by cutting off the top and bottom of the image. Director Don Siegel protested the reformatting, to no avail.

Bronson Canyon was also the location for the tunnel where Miles and Becky hide. A trench was dug for them to lie in with planks placed over them for the scene in which the pod people run through the tunnel looking for them.

Production Designer Ted Haworth was probably the most livid about the studio's tampering. He wrote a letter to Allied Artists' head Steve Broidy, telling him Allied Artists was destroying the picture. Haworth had been Alfred Hitchcock's art director on Strangers on a Train (1951) and I Confess (1953), and he told Broidy that Hitchcock would have given his eyeteeth to have made a picture that frightening.

The picture took only 19 days to make, according to Don Siegel (other reports say as much as 24 days, with about 4 days of studio production). There was no second-unit work and no process shots.

The urbane, genial producer Walter Wanger was liked and respected by everyone involved. However, Kevin McCarthy later said he had the impression during production that director Don Siegel, despite the glowing words he had for his producer in later years, thought Wanger was more diplomatic than effective in his dealings with the front office on such issues as the humor, the title and the additional scenes. "I think he might have called Wanger a pod, if the two of them hadn't been partners," McCarthy said.

A few scenes, such as the interior of Miles Bennell's office, were done at Sunset Studios. The greenhouse scene was also done in the studio because there were so many technical elements to be controlled when the pods burst open and bubbled, revealing the replicas of the characters.

This was one of the first pictures to come under a new Los Angeles smog control regulation concerning the shooting of fire scenes and other special film effects. To schedule the shooting of scenes involving fires, the script first had to be approved by the Air Pollution Control District. Los Angeles County also requested script approval of fire scenes.

Since the movie was filmed at the height of the "Red Scare" in the US, and there were rather blatant attacks on mindless "conformity", it was considered by some to be an attack on Communism, but was considered by others to be an attack on knee-jerk anti-Communism.

An April 1955 "Hollywood Reporter" news item claimed that 38 location sites were used and that only four days of interior shooting were planned.

Included among the American Film Institute's 1998 list of the 400 movies nominated for the Top 100 Greatest American Movies.

Filming was supposed to commence in Mill Valley, north of San Francisco, but the budget wouldn't allow it. In fact, several locations made up the town of Santa Mira, including the actual towns of Sierra Madre, Chatsworth, and Glendale and the areas of Los Feliz, Bronson Caves and Beachwood Canyon, the latter two in the hills above Hollywood. Some interiors were also done on the Allied Artists lot on the east side of Hollywood.

Gig Young, Dick Powell, Joseph Cotten and Richard Kiley were all considered for the role of Dr. Miles Bennell.

Anne Bancroft, Donna Reed, Kim Hunter and Vera Miles were all considered for the role of Becky Driscoll.

When Miles and Becky quote Shakespeare in unison - "I know a bank where the wild thyme grows" - it's technically a misquote. The passage, from Act 2, scene 1, of "A Midsummer Night's Dream," is actually "I know a bank where the wild thyme blows...." However, there is a potential thematic connection. The speaker is Oberon, king of the fairies, and he's sending his messenger, Puck, to pour the juice from a magic flower into the eyes of his sleeping, estranged wife, Titania, so that she will fall in love with the first creature she sees when she wakes up. So the notion of being transformed - of no longer being yourself - after sleeping connects to the plot of this movie.

Director Don Siegel always said he intended the film as a psychological metaphor, not a political one. "There are real people who are essentially pods," he told interviewer Stuart Kaminsky in 1971. He was particularly proud of the scene towards the end in which Miles (Kevin McCarthy) kisses Becky (Dana Wynter) but senses from her nonresponsiveness that she's become a pod. "In my life, sad to say, I have kissed many pods," Siegel told Kaminsky.

Included among the "1001 Movies You Must See Before You Die", edited by Steven Schneider.

Don Siegel cast Kevin McCarthy having worked with him on The Blue and the Gold (1955).

Kevin McCarthy was a good friend of Montgomery Clift but was jealous because in 1956, while Clift was at MGM shooting a prestige big-budget historical extravaganza, "Raintree County," with Elizabeth Taylor as his co-star, McCarthy was making this "B"-budgeted science-fiction movie at a cheap studio. Little did either of them know that eventually "Raintree County" would be virtually forgotten and "Invasion of the Body Snatchers" would be acknowledged as a classic.

Although this was the first Allied Artists film to be shot in SuperScope, Texas Rose (1955) was the first Allied Artists film shot in that process to be released.

On the wall of Jack Belicec's home above the pool table where he shows Miles a pod person that will turn into him, are three posters, presumably the cover art for mystery novels or thrillers Jack has authored: "Chat Blanc," "Mirroir Noir," and "Femme Fatale." They are all French phrases. The third is a familiar term for a stock figure in film noir; the first two translate as "White Cat" and "Black Mirror."

When Miles follows the beautiful music out of the cave and down the mountain (only to find it's coming from a radio station on a truck at a pod farm), just before a worker switches it off the call letters are identified as KCAA. KCAA was not an existing station when this movie was shot in 1955, but in 1964 a station with that call sign debuted in Loma Linda, California. As of 2018, KCAA airs a mix of progressive talk radio shows, live sports coverage, and oldies and classic radio dramas. The call letters stand for Keeping CAlifornia Aware.

In basic terms, the plot of the film resembles that of the book quite closely - apart from the ending and a few other plot details.

As with most low budget movies, the scenes where the pods begin to hatch had to be filmed successfully in one take.

The film originally ended with Miles J. Bennell on the highway shouting to the people driving by, "You're next, you're next!" However, the studio wanted a happier ending that would assure the audience that the hero's efforts were not in vain, so scenes were added to the opening to show Miles in a hospital recounting his story to two other doctors and to the end when the other doctors find out about the pods and one of them contacts the FBI. Players Whit Bissell, Richard Deacon, and Robert Osterloh, who appear prominently in these framing episodes, did not receive screen credit, because their scenes were added after the rest of the film, including the opening credits, had already been completed.

Don Siegel was very against the optimistic outcome of the movie, but the decision to give hope to the audience was forced upon him by the studio. Some people dislike the ending, agreeing with Siegel's original intention to end the film with Miles trying to warn people of the alien invaders, in vain.

The film abandons the novel's ending of the aliens giving up on their world domination plot and returning home.