Bryant Haliday was cast in the lead role as Professor Steiner. He was chosen for the role as Gordon was opposed to a British actor playing the title role, and the budget would not allow a Hollywood star to be used. The fact that Gordon was already familiar with him, as he had cast him in "Curse of Simba" and "Devil Doll", was also a factor. Haliday, a fan of horror movies, enjoyed doing "The Projected Man." British stage actress Mary Peach was cast in the lead role as Dr. Patricia Hill. It was insisted that she be given top billing for her role. Norman Wooland, a German-born British character actor, was cast as Dr. Blanchard, the film's villain. Derek Farr portrays Inspector Davis, and Ronald Allen plays the role of Dr. Christopher Mitchell. A scene in the film features actress Norma West lying topless on a morgue table; this scene was added to aid sales overseas.