This film was rarely seen for many years, as it was the only entry in the trilogy to never to receive a videotape or laserdisc release. It did not receive its home video premiere until 2007, when it was released on DVD in a box set with the original series of films.
Vincent Price is missing from this, the third and final installment of the series. By this time this was produced, Price was under contract to American International Pictures.
Claude Rains was going to play Henri Delambre at one stage.
Many say that this movie has no connection with the original The Fly (1958) and Return of the Fly (1959) mainly because no Fly monster is shown, but, the central character with the last name Delambre, a photo showing the Fly during a conversation about the family legacy, the new version of the matter transporter machine, and a scene with Inspector Charas (played by a different actor), this film definitely has connections to both of the previous two Fox films in this trilogy, The Fly (1958), and Return of the Fly (1959). Produced on the cheap in England, it was a box office bomb because audiences wanted to see a man with a fly head. Sorry no Fly monster in this movie. This was the last Fly movie released by Fox until the 1986 Jeff Goldblum/Geena Davis remake. Of course, the movie completely changes the backstory, mythos, motivations and plots of the first two movies and all of its characters. Even Inspector Charas has a completely different relationship to the Delambre's than he does in the first two movies. If anything, this movie is a completely new story in the series that just happens to share character surnames.
Charles Carson replaced Herbert Marshall.
The house servant named Tai and his wife named Wan. Taiwan.