Trivia

Christopher Lee (Dr. Charles Marlowe / Mr. Edward Blake) previously played Paul Allen in The Two Faces of Dr. Jekyll (1960), another film adaptation of Robert Louis Stevenson's 1886 novella "Strange Case of Dr. Jekyll and Mr. Hyde."

Peter Cushing was quoted later on saying that this was one of the least enjoyable films of his career.

This film attempts (and is mostly successful in doing so) to exploit the Pulfrich effect to provide a 3-D experience. To see this, use a pair of glasses with the right lens much darker than the left. These are available for other videos or they can be made by removing the left lens from a pair of sunglasses. Some clever camera work and choreography that keeps the foreground moving to the right and the background moving left makes this possible.

According to director Stephen Weeks, this film ran out of money before it was even completed.

The Italian-dubbed version of this film was re-titled "La Vera Storia del Dottor Jekyll" ("The True Story of Dr. Jekyll") and restored the character names of Dr. Henry Jekyll and Mr. Edward Hyde from the original 1886 novella.