Elmer Bernstein composed the score.
A skydiving team called the Gypsy Moths visits a small town in Kansas to put on a show. Their leader, Mike Rettig (Burt Lancaster), is accompanied by his partners, Joe Browdy (Hackman) and Malcolm Webson (Scott Wilson).
The skydivers stay at the home of Malcolm's uncle and aunt, John and Elizabeth Brandon (William Windom and Deborah Kerr). Distractions begin almost immediately when Mike becomes romantically involved with Elizabeth, whose husband overhears her making love with Mike in their home. Malcolm falls for local student Annie Burke (Bonnie Bedelia), a boarder in the Brandon house, while Joe takes an interest in a topless dancer.
Mike eventually asks Elizabeth to leave town with him, but she declines. During the next skydiving exhibition, Mike intends to do a spectacular "cape jump" stunt, but fails to pull the ripcord, and hits the ground at over 200 miles per hour. Although nobody wants to discuss it, there is a suspicion that he committed suicide. That night, Annie consoles Malcolm, and they make love. Before the team leaves for good, they have to bury Mike. To pay for the funeral, Malcolm does the same stunt that killed Mike. He leaves by train that night without attending Mike's funeral.
The remarkable aerial sequences in The Gypsy Moths were filmed at 12 locations in and around Benton, Kansas, with a Howard DGA-15 (N22418) used as the jump ship, flown by David Llorente. Hackman (as Joe Browdy), after decoding the "DGA" designation, jokes that "You're much better off jumping out of it, than taking a chance on landing it."
At the time, the sport of skydiving was in its infancy, yet the film featured an extreme variation of the sport, the use of "batwings", a precursor to modern wingsuit flying. Todd Higley, a prominent skydiver in the Seattle area today, was a key technical advisor and stunt double for Lancaster, and today is well known for having invented wingsuit BASE jumping. Carl Boenish was responsible for the aerial photography, including photographing the jumps with a 35 mm camera mounted on his helmet, while he jumped with the stunt doubles, a team of a dozen skydiving enthusiasts.
John Phillip Law was originally in the cast, but Scott Wilson replaced him after Law broke his wrist.
The Gypsy Moths ran in limited release in the U.S. and saw few theaters giving it extended showings. Frankenheimer was depressed and felt that a regime change at MGM resulted in the film only being partially re-edited "so it could debut at family-friendly Radio City Music Hall, where it promptly bombed. Only in Hollywood could dealing with clueless studio executives be more frightening than jumping out of an airplane into free fall."
In his review for The New York Times, Vincent Canby noted that The Gypsy Moths had the semblance of an "action film," but "if this were a real action movie, I would be required to do little except look up at the sky and squint. Unfortunately, there isn't that much skydiving."
After its initial showings, the film was lengthened to 110 minutes and the rating changed to M for mature audiences. This rating was an early version of the later R. As soon as it appeared, The Gypsy Moths disappeared. Director Frankenheimer claimed the film did not get the same attention as his thrillers, like Seconds (1966) and The Manchurian Candidate (1962). Despite this, he would call The Gypsy Moths one of his two favorite films.
The Gypsy Moths was widely seen in Australia, with a local skydiving fraternity quick to seize the opportunity to promote their sport, showing a 16 mm print at many club meetings.