Jack Nicholson claims to have nearly drowned while filming in the surf of Big Sur.
Sandra Knight was pregnant while filming.
Francis Ford Coppola took eleven days to shoot his second unit footage, only ten minutes of which wound up in the finished film.
Roger Corman decided on a major change for this film. Instead of a fire, the usual finale for a Corman film of the period, he had the castle flooded instead. Corman's crew had come to look forward to "fire day".
Roger Corman shot the bulk of the film in four days, but the second-unit work was filmed over a nine month period by five directors, Francis Ford Coppola, Dennis Jakob, Monte Hellman, Jack Nicholson, and Jack Hill.
Roger Corman shot the castle scenes with Boris Karloff so quickly that he didn't even bother to use slates to mark the beginnings of shots. Once he just had the actors walk downstairs one after another in succession, figuring he could later cut the single shot into separate shots that he could probably use somewhere.
A shot involving quicksand was directed by Jack Hill in his own backyard. The quicksand was originally planned for the death of Jonathan Haze's character, until it was decided to have him attacked by a falcon.
Although Boris Karloff's scenes were captured in four days, the remainder of the film was shot over the course of nine months, making it not the shortest Roger Corman production but one of his longest.
Having finished The Raven, Roger Corman immediately shot this film using the same sets and the same two lead actors. All of the scenes involving Boris Karloff were filmed by Corman in four days, but the finished film, which was largely improvised, required nine months to complete, the longest production of Corman's career.
Sets for both The Raven and The Haunted Palace were reused in this film. The tree that Sandra Knight rots against at the end was the one to which Vincent Price was tied and burned in "Haunted Palace."
The original theater poster warned its patrons: "No one will be admitted while the coffin is being opened!"