The movie's novelization was published in 1982 by science-fiction writer Dennis Etchison under the pseudonym Jack Martin. Despite the movie's critical failure, the book became a best-seller and was even reissued two years after the movie's release, in 1984.
John Carpenter didn't plan on having Michael Myers in another Halloween movie, only the first. He wanted a different Halloween related story each time, but after the first La Nuit des masques (1978) was a success, producers forced him to use Myers again. He did, but killed off Myers and Loomis to be done with them. Then he produced Season of the Witch to get back to his original plan, but at that point, people were expecting Myers again, so it failed. Carpenter then sold the rights years later, because he wasn't interested in doing more Myers. The new owners then brought Myers and Loomis back in 1988 with little explanation how they survived.
(at around 28 mins) When Challis fills in the register at the motel office, he scans the list of names for evidence of Ellie's father's stay. Most of the other names on the list are the names of the crew.
Using the original molds, the skull, witch, and jack-o'-lantern masks seen in the movie were mass-produced by Don Post Studios and sold in retail stores to promote the movie's release.
(at around 1h 19 mins) It took over forty takes to get the shot when Tom Atkins throws the skull mask on the security camera. Director Tommy Lee Wallace revealed during the cast's 2015 reunion that the scene took longer than he expected, because during the shoot he playfully tossed the mask and it caught on the very first try.
Jamie Lee Curtis: (at around 55 mins) The voice of the operator that Challis keeps getting when he tries to call out of Santa Mira is Jamie Lee Curtis.
Jamie Lee Curtis: The star of the first two movies provides the voice over the intercom, informing Santa Mira residents of the 6pm curfew (at around 31 mins).
Nancy Kyes: Dr. Challis' ex-wife and mother of his two children. Kyes (aka 'Nancy Loomis') played Annie Brackett in La Nuit des masques (1978) and briefly in Halloween II (1981).