In an interview, star Marshall Thompson recalled that director Arthur Crabtree didn't really want to direct the film--he thought sci-fi was beneath him. Crabtree turned up on set on the first day of filming, took one look at the script and informed the cast and crew that he refused to do the film. He walked off set, and the producers needed several days to convince him to return, citing contractual obligations. Thompson says that during those days, Thompson directed the film himself.
A publicity stunt went somewhat wrong in New York City. The Rialto Theater in Times Square featured a sidewalk promotion for the film--one of the prop brain creatures was displayed in a cage on the sidewalk outside the theater, wired for sound and motion. However, the crowd it attracted grew so large that they were snarling pedestrian and vehicle traffic, and the police demanded that it be removed.
Considered so horrific that the controversy was reportedly brought up in Britain's House of Parliament.
Kim Parker only appeared on screen in a towel for a few seconds, but the studio used that image on the posters to promote the movie. The shocked look on her face wasn't caused by the creatures in the film; she was startled to find a man in her bedroom as she walked out of the bathroom half-naked.
There were reports of some audience members being sickened by what they saw on the screen. It is not known how many of the stories about fainting and sickness were genuine or simply examples of old-fashioned Hollywood ballyhoo.