Dino De Laurentiis originally hoped that Federico Fellini would direct this film. The director had actually contributed to the original Flash strip cartoon during WWII.
Kurt Russell auditioned to play Flash Gordon. According to an interview with Russell in Starlog magazine from August 1981, Dino De Laurentiis really wanted Russell for the part, but he ultimately turned it down because Russell thought the character was lacking in personality.
Nicolas Roeg was originally going to direct, but didn't due to creative difference. One of his proposals was to excise the trademark cliffhangers and melodrama, seeing Flash as more of "a metaphysical messiah."
Director Mike Hodges, referring to the numerous production problems that plagued the film, once called it "the only improvised $27-million movie ever made".
The backstory of Flash's T-shirt was that it was a gift from an anonymous female fan. Flash wore it a lot in the hopes that he would eventually meet the woman.
In the original script, when Flash is sentenced to death by Ming, Dale bursts out that Ming is "absolutely merciless". Ming is enthralled with the description, and immediately starts calling himself "Ming the Merciless".
According to the original storyline, when Dale is entranced by Ming's hypnotic ring, she is having a vision of being on an erotic picnic with Ming in a 1920's setting.
Klytus and Kala, Ming's two chief henchmen, were competitors for their ruler's favor. Ming played them off against each other to keep them from teaming up against him. This was downplayed in the film to keep the storyline fluid.
In the original script, Flash and Dale first meet at a Canadian resort called Dark Harbor. Although they flirt with each other, they don't become acquainted until they're sharing the ill-fated plane ride to New York City. Dale later talks briefly about Dark Harbor during her tear-filled meeting with Flash before his execution.
Dr. Zarkov's backstory was that he was a NASA scientist who was fired for his paranoid fantasies that Earth was going to be attacked from outer space. Sixty Minutes derided him as "A Poor Man's Billy Mitchell".
Ming's attack on Earth was accomplished by bombarding the moon with force beams, knocking it out of orbit. The meteors which disrupt Flash's airplane flight were burning chunks of lunar debris.
Sam J. Jones' dark hair was bleached blonde for this role, and Melody Anderson's blonde hair was dyed brown. Flash was also supposed to have blue eyes, but Sam could not wear the contact lenses.
Ming's symbol (which Klytus also wears on his gauntlets) is borrowed from the Freemason's square and compass. Ming also makes a Masonic gesture during the course of the movie.
The wristwatch Flash is wearing in the early scenes of the film is a Seiko automatic chronograph, model 6139-6002. The watch disappears when Flash gets to Mongo.
Most of Sam J. Jones's dialog was dubbed. This was down to the fact that Jones had had a falling out with producer Dino De Laurentiis over lack of payment and refused to go into the recording studio to loop his lines.
This was the first movie that the rock band Queen made the music for, in it Prince Vultan says "Who wants to live forever?". The only other movie Queen did the soundtrack for was Highlander, for the movie they wrote a song called "Who Wants to Live Forever."