Gelt is modeled closely after the character Lee from The Magnificent Seven, on which this film was based (Robert Vaughn played both). Some of Gelt's dialogue is lifted almost verbatim from "The Magnificent Seven".
The natives of Akir are known as the Akira. This is no doubt a tribute to legendary director Akira Kurosawa (whose film Seven Samurai served as the inspiration for this film).
Screenwriter John Sayles had originally envisioned the character of Cayman as a brooding dark humanoid, not the lizard alien seen in the final product.
This was Roger Corman's most expensive feature up to that time, costing $2 million. Most of the budget was spent on salaries for Robert Vaughn and George Peppard, who both had high asking prices.
Future director James Cameron and future producer Gale Anne Hurd met on this film and decided they wanted to work together (the deal was that Cameron would direct and Hurd would produce). This would lead up into making The Terminator, their marriage in 1985 before they did Aliens, and their divorce to both marriage and creative partnership during making of The Abyss.
According to an interview with star Richard Thomas, the wardrobe department had a difficult time keeping the top of Sybil Danning's costume on and had to resort to using band aids to prevent said top from slipping off.
A View-Master 3-reel packet was issued featuring 21 images from the movie. It's also the only one of Roger Corman's films to be marketed with a View-Master tie-in. A booklet was issued with the packet that included a bondage image showing Nanelia tied up as a prisoner of the reptilian Cayman. A French language version of this pack issued for the Canadian market.