Basil Rathbone was paid $1,500 to act for a day and a half on this film and $1,500 for half a day on Voyage to the Prehistoric Planet (1965), another film that incorporated Russian film footage. Rathbone ended up working overtime and missed a meal. The Screen Actors Guild demanded overtime pay, plus a fine for the meal violation, but producer George Edwards produced footage that showed the delay was because Rathbone had not memorized all his lines and insisted on skipping lunch.
This was an ultra low budget production. The elaborate special effects were taken (uncredited) from two big budget Soviet productions, Mechte navstrechu (1963), and Battle Beyond the Sun (1959).
John Saxon later claimed that Gene Corman had more to do with this movie than Roger Corman. Saxon estimated that his scenes were shot in seven to eight days, and that Dennis Hopper "was trying very hard to keep a straight face throughout" during the making of the film.
Czech actress Florence Marly was a personal friend of Director Curtis Harrington. He later said that he had to fight with Roger Corman in order to hire her "because she was an older woman". Harrington would say, "I'm sure he had some bimbo in mind, you know? So I fought for Marly because I felt she had the required exotic quality that would work in the role." Harrington also said Dennis Hopper "was like a part of my little team by then", so he agreed to also appear.
Director Curtis Harrington felt that Ridley Scott's Alien (1979) must have received some inspiration from his feature, saying "Ridley's film is like a greatly enhanced, expensive and elaborate version of Queen of Blood."