To increase the pendulum's sense of deadly menace, director Roger Corman took out every other frame during the editing stage making the blade appear to move twice as fast.
This was the second of Roger Corman's Edgar Allan Poe films. He had intended to do "The Masque of the Red Death" but felt that it was too close to the content of Ingmar Bergman's recent The Seventh Seal (1957). Several years later, Corman would go to England to make The Masque of the Red Death (1964).
The film did not have an original prologue. It was added when the film was sold to TV and a further few minutes were required to pad out the running time. Only Luana Anders from the original cast was available, so an extra scene of her in a madhouse was filmed and tacked onto the beginning. This scene does not really tie in with the rest of the film.
This film was shot in 15 days.
Actor John Kerr was worried about being strapped down to the table with the pendulum above him for the movie's climax. In order to demonstrate that it was perfectly safe, director Roger Corman stood in for Kerr while the scene was being set up.