- Actor Allusion: Pamela Franklin dealing with ghosts possessing people? She's done that before, and this time it's definitely real.
- Billing Displacement: Pamela Franklin is billed first, despite Lionel being the clear protagonist of the story. This is due to the cast getting billed in alphabetical order.
- The Cameo: Michael Gough as the corpse of Belasco. He also provides the voice, but is uncredited.
- Dawson Casting: A line from Florence states that Ben was fifteen in 1953. The film takes place twenty years later, placing Ben at thirty-five or thirty-six. Roddy McDowall was in his late forties at the time.
- Real Life Writes the Plot: The novel is set in America, but the film changed this to England, due to being produced over there.
- Star-Derailing Role: Despite the film being a success, it unfortunately typecast Pamela Franklin as a scream queen. Before she had been riding high with a BAFTA nomination for The Prime of Miss Jean Brodie. She would make one more film and spent the next decade doing TV movies and guest spots on television before retiring completely in 1981.
Trivia / Hell House