The flamethrowers used in the movie were standard World War II weapons, and were loaned by the U.S. Army. The actors handling the weapons were World War II combat veterans who had used them in battle.
Walt Disney screened the movie because he was interested in casting James Arness as Davy Crockett. However, he was so impressed by Fess Parker as the "Crazy Texan Pilot", that he chose him for the part.
The viewer never sees more than three giant ants at any one time. That is all that were constructed.
In 1998, Joan Weldon revealed that during shooting, the temperature reached one hundred ten degrees Fahrenheit (forty-three degrees Celsius), and both she and Edmund Gwenn were wearing wool clothing. It was even more insufferable for Gwenn, who struggled with advanced arthritis. Although unnoticeable to audiences, he was in pain and was helped off-set by his valet.
The film was originally to have been filmed in color. Two days before shooting began a nervous studio cut the budget, and the film had to be made in black and white. However, in the opening credits, the title is shown in bright red against a black-and-white background.
Was originally to have been shot in 3-D. Some elements of the 3-D effects, such as the ants having extreme close-ups and the flame throwers shooting straight into the camera, were used. Although the second eye print was filmed, it was never struck,and likely destroyed later.
The old man singing "Make me a Sergeant" is the same old man that played the actor in The Blob (1958) with the thing on his arm.
The sound that the giant ants make as they approach their prey is a recorded chorus of bird-voiced tree frogs (Hyla avivoca) of the southeastern U.S. Occasionally, a gray tree frog (Hyla chrysoscelis) can be heard on the soundtrack as well, as these species can often be heard together at the same wetland. These distinctive whistling-type sounds were re-used in various other films in the years that followed, particularly in Mohawk (1956) and The Black Scorpion (1957).
Director Gordon Douglas recalled that during editing, "I asked the editor, 'How does it look?' And he said, 'Fine.' I said, 'Does it look honest?' He said, 'As honest as twelve-foot ants can look'."
When this movie was first released in Sweden, it was strangely named "Spindlarna", which translates as "The Spiders".
The B-25H Mitchell bomber transporting the doctors Medford was actually the personal transport for a two-star general. This aircraft was registered as N1203, and was also a camera plane for Catch-22 (1970). The pilot seen taxiing this aircraft in the opening scene appeared to be Paul Mantz, the famous Hollywood movie stunt pilot. He was killed filming the Phoenix P1 airplane seen in The Flight of the Phoenix (1965).
The subterranean chase scenes in He Walked by Night (1948) convinced a Warner Brothers executive to use the storm drain tunnels under Los Angeles, California for the climactic scenes in this film. The original story idea to have the giant ants invade New York City's subway system was scuttled partly due to budget constraints, but mainly because of the horrified reaction of New York City Transportation Secretary William J. Daley to such a suggestion.
No giant ant is seen until twenty-eight minutes in, more than one quarter of the way through the movie.
The camera Dr. Pat Medford (Joan Weldon) was using in the helicopter was a Stereo Realist, which was a 35mm format stereoscopic (3-D) still camera. This is both perfectly natural and ironic, since the film itself was originally planned as a 3-D release.
Inspired a quest in the game Fallout 3 (2008) titled "Those", in which the player must eliminate a colony of giant fire ants.
Shortly after the helicopter reconnaissance, a meeting opens with an Army officer looking through a Stereo Realist red button viewer. He is evidently looking at 3-D slides taken by Dr. Patricia Medford (Joan Weldon). A second viewer is on the table next to Dr. Medford. This was rather clever product placement, considering the film was originally slated to be shot in 3-D format.
In street scene, when martial law is declared, seen on movie marquee is the title 3 Sailors and a Girl. It is also a Warner Brothers film in 1953.
Regarding the "S.S. Viking" incident, there was no cruiser named "U.S.S. Milwaukee" in commission in the US Navy at the time this film was made. The last ship so named was an Omaha-class light cruiser (CL-5) which was commissioned in 1923 and scrapped in 1949 after service in World War II in both the U.S. and Soviet navies. The next ship named "Milwaukee" would be a Wichita-class replenishment oiler (AOR-2) that would be in service from 1969 until her decommissioning in 1994. Her name was stricken from the Navy's list in 1997, and as of 2007, she is awaiting final disposal at the James River Reserve Fleet, Fort Eustis, VA.
While James Arness starred in this movie, his brother Peter Graves (born Peter Aurness) later starred in one of its many imitators, Beginning of the End (1957).
This film is mentioned in Stephen King's famous best-selling novel, "It."
In the movie, James Whitmore and James Arness battle the giant ants with machine guns, flamethrowers, and bazookas, while wearing Army uniforms, although neither of their characters is technically a soldier. (Whitmore is a New Mexico State Trooper, and Arness is an F.B.I. Agent.) However, Whitmore and Arness had previously appeared together as soldiers in combat in Battleground (1949).
Warner Brothers initially passed on this picture and expressed little interest. However, when Paramount offered to pick it up, Warners dropped their objection, although they eventually eliminated the 3-D and color aspects. It's hard to understand their little faith in the picture, since The Beast from 20,000 Fathoms, Ray Harryhausen's first solo effort, had been one of Warner's biggest hits just the year before (1953).
WILHELM SCREAM: Can be heard four times. When the giant ants attack the crew of the ship at sea, when Police Sgt. Ben Peterson (James Whitmore) was throttled by a giant ant, when a soldier is struck by falling debris in the sewer and when James Arness gets separated from the rest of the Army and ants try to attack him. The ceiling falls in, and while he is reloading his weapon an ant tries to attack him. There's also a scream off-screen from Peterson's partner, Ed Blackburn, when he investigates the sounds made by the ants.