Only one robot costume was constructed for this film and it was used for all robot scenes. This is why you never see more than one member of the "robot army" in a shot.

Robert Roark (who played the killer) got his part because his father, a doctor in L.A., would only invest in the film if his son was given a part. After this part Roark went on to play in many movies and eventually became a producer.

Although the production crew had no permits, the scenes showing the deserted city were filmed in downtown Los Angeles on Sunday mornings when the streets would be vacant.

The film came in under budget, spending only $85,000 of the $100,000 allotted by its main investors DeLuxe Labs and Allied Artists.

Richard Denning's character is from Detroit, which was also producer Herman Cohen's home city.