Creator Backlash: Nigel Kneale was the original writer of the film, when producer Dino De Laurentiis demanded that the movie become darker and gorier, Kneale began to object, but went unheard. When he saw the final product he asked Carpenter to take his name off the project, left, and never worked on another major movie again (aside from some British TV horror films).
Stillborn Franchise: This version was intended to turn the film series into a horror anthology; when it failed with critics, every other movie returned to the Michael Myers plotline and stuck to it like glue.
What Could Have Been: If the reception for this one hadn't been so negative, Carpenter might have been able to continue with his original idea of making Halloween an anthology series with a fresh plot and characters for each movie. The only unifying thread would have been that they all take place on Halloween — the possibilities would have been endless.
The original script was apparently more of a tongue-in-cheek mystery film that seemed to be aware of the ludicrous concept, Executive Meddling killed it before filming.