The mutants were played by members of the Los Angeles Lakers.
Producer Ray Dorn "borrowed" much of this movie for Journey to the Center of Time (1967). Irwin Allen also borrowed much of the concept for his TV series El tunel del tiempo (1966). Director Ib Melchior declined to make waves so he would continue getting work in Hollywood.
Forrest J. Ackerman's cameo appearance led him to make numerous cameo appearances, and even do bit parts, for more than 40 years.
Peter Strudwick personally contacted Ib Melchior about possibly playing the role of a monster in this film. After visiting Melchior at his house, Melchior wrote the part of The Mutant for Strudwick to specifically portray.
Gene Roddenberry saw this film whilst in the process of writing the pilot script for Viaje a las estrellas (1966). When pitching the idea to Desilu studios, who were concerned by the costs, he took them to see this film to show what could be done on a limited budget. They then ended up hiring some of the production personnel who had worked on this film to design and build the sets and costumes for the TV show. They also hired actor John Hoyt (who plays Varno in this film) when casting for the pilot show The Cage (1966)).
Forrest J. Ackerman: In addition to being the editor of "Famous Monsters of Filmland" magazine, also happened to be writer/director Ib Melchior's literary agent.