Trivia

The sinking of the yacht and several shots of the cat in the ocean were filmed in Greydon Clark's swimming pool.

75,000 dollars of the film's 200,000 dollar budget went to the salaries for George Kennedy, Alex Cord, and Clu Gulager.

An earlier draft of the script had a rat instead of a cat in it.

Greydon Clark paid fifteen thousand dollars to rent the yacht used in the film for two weeks.

Several scenes were shot in Greydon Clark's garage.

Greydon Clark: Research scientist, Dr. Grey.