Author Existence Failure: David Warbeck had written a screenplay for a sequel to the film but his death put an end to it ever seeing the light of day. Blackest Heart Media DID buy the rights to make a comic adaptation of the script, but went out of business before production of it began.
Executive Meddling: The film was supposed to be a straight-up surrealistic gore film about a haunted hotel where people die horribly. Fulci's distributors demanded a zombie shoot-out, hence the side trip to the hospital in the third act and the twist that the hotel's vast basement is connected to EVERY major building in town.
Keep Circulating the Tapes: The film was extremely popular on the Euro-Horror tape trading scene, thanks to fans who ripped the uncut version off of an uber-rare laser disc version of it.
No Export for You: The uncut version was widely unavailable in the US for a long time.