Medical schools, at least as late as the 1980s, would show clips from this film to illustrate various concepts in human anatomy, physiology, and especially immunology.

The time spent in the movie of the crew once they were miniaturized is in real time, taking up almost exactly one hour of the movie.

When filming the scene where the other crew members remove attacking antibodies from Ms. Peterson for the first time, director Richard Fleischer allowed the actors to grab what they pleased. Gentlemen all, they specifically avoided removing them from Raquel Welch's breasts, with an end result that the director described as a "Las Vegas showgirl" effect. Fleischer pointed this out to the cast members - and on the second try, the actors all reached for her breasts. Finally the director realized that he would have to choreograph who removed what from where, and the result is seen in the final cut.

A now defunct thrill ride at Disney's Epcot Center, called Body Wars, was largely inspired by this film, even though it is not a Disney film. The director, Richard Fleischer, however, also directed Disney's first science fiction film, 20,000 Leagues Under the Sea (1954).

Voyage to the Bottom of the Sea (1964) reportedly 'borrowed' props from the elaborate sets of this film for an episode in which a diving bell is swallowed by a huge whale.

The scenes of crewmembers swimming outside the sub were shot on dry soundstages with the actors suspended from wires. There was some additional hazard involved because, to avoid reflections from the metal, the wires were washed in acid to roughen them, which made them more likely to break. To create the impression of swimming in a resisting medium, the scenes were shot at 50% greater speed than normal, then played back at normal speed.

During filming, one of the two 3-inch "Proteus" models used in the miniaturization sequence was left by an open window and was subsequently carried off by a crow.

In his book, special effects man L.B. Abbott writes about making use of a giant champagne glass built for another movie to fill with water and use for the whirlpool sequence when the ship is sucked through a tear in the artery. Althougth he doesn't mention the movie's name, it is most likely the film What a Way to Go! (1964) which had a sequence of Shirley MacLaine lounging in a giant champagne glass.

The scenes in the spacious corridors of the secret CMDF medical facility were filmed in lower and upper concourses of the Los Angeles Memorial Sports Arena. Director Richard Fleischer would later use the arena for exteriors in Soylent Green (1973).

Isaac Asimov was approached to write the novel from the script. He perused the script and declared it to be full of plot holes. Receiving permission to write the book the way he wanted, delays in filming and the speed at which he wrote saw the book appear before the film.

It is never explained why the Proteus crew must communicate by code rather than voice transmission.

The sound effects played over the opening credits were created for the computer in Desk Set (1957).

Original on-screen acknowledgment appearing after the end credits: "The makers of this film are indebted to the many doctors, technicians and research scientists, whose knowledge and insight helped guide this production."

As a college student, director Richard Fleischer was a pre-med student for a time.

The jetliner seen in the opening of the film, a TWA 707 registration N746TW, had a long life and carried passengers from 1962-82. It was then mothballed at the Davis-Monthan storage facility and cannibalized for repair parts for the US Air Force fleet of KC-135 tankers. It was eventually scrapped.

The plot of this movie was partly borrowed for the first-season episode I Dream of Jeannie: The Moving Finger (1965). In that episode, Capt. Nelson works as technical consultant for a studio making a movie, in which an American astronaut, shrunken to the size of a pinhead, is injected into the bloodstream of a Soviet astronaut, works his way to the brain and retrieves information vital to the defense of the country. The screenplay to "Fantastic Voyage" was completed in 1964, from an original story that was written in 1963.

The design and special effects were considered cutting edge at the time, so much so that they received a photo spread and article by Richard Schickel in Life Magazine.

The miniature brain sets were used to represent the interior of the alien spacecraft in Lost in Space: The Derelict (1965).

Raquel Welch said in her 2013 book that she was infatuated with actor Steven Boyd in making the film. Although he declined her advances.

Original on-screen prologue appearing immediately after the opening 20th Century-Fox logo and fanfare: "This film will take you where no one has ever been before; no eye witness has actually seen what you are about to see. But in this world of ours where going to the moon will soon be upon us and where the most incredible things are happening all around us, someday, perhaps tomorrow, the fantastic events you are about to see can and will take place."

The film was produced the same year as the original Lost in Space series. If you pay attention to the sets and sound effects you can sense the similarities.

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

During their emergency trip through the arrested heart, the crew has 57 seconds to accomplish this safely. The scene from stoppage to restart lasts over 3 minutes.

There have been several high profile attempts to remake "Fantastic Voyage" over the years with James Cameron, Roland Emmerich and Will Smith, Paul Greengrass, and most recently Guillermo del Toro, all attached at various stages.

The Los Angeles Memorial Sports Arena, used for interior filming, was demolished in 2016.