Old theatrical recordings of Spanish horror icon Paul Naschy's voice were used to provide the voice of an automated wax figure featured in the wax museum.
All the gore effects for this film were done live and practically in camera.
At the end of the film, actress Geraldine Chaplin pauses to look at a wax statue of Charlie Chaplin, her real life father.
Paul Naschy died years before of the filming, and actually didn't act in the movie. His performance was made with an old record of his voice, without relation to the movie.