Director Lucio Fulci always carried around a bag with his trademark pipe and tobacco. One day on set, he reached into his bag and found a handful of maggots (which had been used earlier to film the scene in which maggots blow in through a window). The perpetrator of this prank is rumored to be Christopher George, the film's lead actor, who did not get along well with Fulci.
Each German release was banned over the course of over 20 years. The movie was first released on video with the title "Ein Zombie hing am Glockenseil" (A zombie hung on the bell rope) in 1982. It was banned in 1986 and a second video with the title "Ein Toter hing am Glockenseil" (A dead body hung on the bell rope) was released, with several cuts. Even that version was banned in 1988 and a final version was released with the title "Eine Leiche hing am Glockenseil" (A corpse hung on the bell rope), heavily cut without any gory scenes left. Rumors say the video distributors actually designed a new video release called "Ein Kadaver hing am Glockenseil" (A cadaver hung on the bell rope) in case this third version will get banned again. Surprisingly, this third version was also banned in 2001.
When theatrically released in the United States in 1983, the original title was 'Twilight of the Dead.' Due to the fact that both the title and poster art were derivative of Dawn of the Dead (1978), United Film Distribution Company filed a cease and desist order against Motion Picture Marketing. Posters and prints of the movie bearing the title 'Twilight of the Dead' were pulled, altered and sent back out with the new title 'The Gates of Hell'.
The character "Bob", played by Giovanni Lombardo Radice, was originally intended to be a hunchback. However, Radice decided against wearing the hump that was made for him, and instead portrayed the character having a stiff, lurching gait.
The Book of Enoch is a non-canonical Jewish religious work going back to the 4th Century BCE. It is considered canon by the Ethiopian Orthodox Tewahedo Church and the Eritrean Orthodox Tewahedo Church, but not by any other Christian groups.
The trivia items below may give away important plot points.
For Daniela Doria's death scene, in which her character vomits up her internal organs, the actress swallowed and regurgitated a plate of tripe. In closeups a fake head was used, which contained a pump that spewed the organs out more forcefully.
There are a ton of explanations for how the end took the shape it did, and neither Lucio Fulci nor Dardano Sacchetti was ever of any help straightening it out. Some say the editor spilled coffee on the footage of the original ending, forcing the crew to improvise. Some say Fulci changed his mind about the end after the shooting was complete, and this was the best they could do.