- A door that Christopher Lee must crash through is accidentally bolted by a grip before the scene is shot. Lee's shoulder is dislocated when he breaks down the door, but the shot remains in the movie.
- The squibs used when Peter Cushing shot Christopher Lee left burn marks for weeks. Lee also threw his back out carrying the girl.
- Hammer Films had already done remakes of Frankenstein and Dracula. This was the first film made after Hammer reached an official agreement with Universal (then Universal International) allowing them to do remakes of their classic horror films. In this film, for example, the agreement with Universal allowed them to use the name "Kharis".
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