Jack Nicholson claims to have nearly drowned while filming in the surf of Big Sur, CA.

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.

Francis Ford Coppola took 11 days to shoot his second-unit footage, only ten minutes of which wound up in the finished film.

Having finished The Raven (1963), 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.

Since the credits feature no copyright information, the film is in the public domain.