- After the success they had with The Texas Chainsaw Massacre 2, The Cannon Group had reached out to Debra Hill and John Carpenter about producing a Halloween IV. After a draft was written by Dennis Etchison, The Cannon Group ultimately passed on the project. Shortly thereafter, Debra Hill and John Carpenter sold off their rights to Moustapha Akkad.
- Alan B. McElroy wrote the script in eleven days and beat the 1988 writer’s strike – which wound up lasting for five months – by mere hours.
- Similar to the production of the original film, leaves had to imported and squashes were used as stand-ins for pumpkin to mask the spring shooting schedule.
- Ellie Cornell and Danielle Harris were required to be on set for 36 of the film’s 41 production days.
- While the first three films were shot in a 2.35:1 aspect ratio, Halloween 4 was shot in a 1.85:1 ratio. At the time, it was cheaper to use cameras with the latter aspect ratio over the former.
- Tom Morga was originally cast to play Michael Myers, as was replaced with George P. Wilbur after production had already began. Though some of the scenes with him as the bandaged, pre-mask Michael appear in the film, he was not credited for them.
- Danielle Harris was allowed to keep her clown costume, and Ellie Cornell got to keep the jean jacket that Rachel wears.
- George P. Wilbur would often take his mask off between takes and play with Danielle Harris to prevent her from being scared during filming. Danielle Harris has often said she was aware that it was all make believe from the get-go regardless.
- Jamie Lloyd’s name was originally scripted as Britti, but was later changed to Jamie as an homage to Jamie Lee Curtis.
- Additionally, as Jamie is a derivative of James, fan speculation has led to the common theory that Jamie Lloyd is the daughter of Laurie Strode and Jimmy from the second film. This has never been confirmed.
- Rachel’s friend that drives them to the convenience store was intended to be Lindsay Wallace from the first two films, who would’ve had a bigger part in the film. Her character was cut down as a result of budgetary restrictions.
- The third teenage boy hanging out with Brady and Wade in the convenience store was intended to be Tommy Doyle as well.
- The school scene originally contained a sequence where Jamie Lloyd hid under the tables and Michael would flip them. Cut due to timing restrictions, Moustapha Akkad remained a fan of the scene and had it included with Jamie Lee Curtis in Halloween H20.
- This is the first Halloween film to have a masked Michael Myers credited as Michael Myers rather than The Shape in the end credits.
- The photo of Laurie Strode in Jamie’s shoebox was an actual promotion still taken of Jamie Lee Curtis for the original film.
- This is the first film in the franchise that shows Michael Myers killing someone before Halloween as he kills the EMTs on October 30.