Director Cameo: [Lucio Fulci] the librarian who goes out to lunch, right before the Architect is attacked by the spiders.
The zombie rampage was done at the insistence of the film's German distributors whose movie market was going through a zombie craze.
Director Lucio Fulci had his Zombi 2 (1979) star Tisa Farrow in mind for the lead in this film, but Farrow had left the acting profession.
The role of the blind girl Emily was originally offered to Stefania Casini who declined it.
Director Cameo: [Lucio Fulci] when David Warbeck answers the phone at the Jazz saloon, the director is reflected in the mirror behind him.
The DVD commentary by actors Catriona MacColl and David Warbeck was recorded two weeks before Warbeck's death from cancer. In the commentary he talks about his illness.
This film was never seen in America in its uncut form until 1998, when Quentin Tarantino's Rolling Thunder Pictures, in association with Grindhouse Releasing, tracked down the original master and restored the film, playing it at midnight shows at selected cities. Bob Murawski of Grindhouse Releasing is a film editor, and used a shot from this film in the spider-bite dream sequence in Spider-Man (2002).
During the final scene in the Beyond's abyss, the sand-covered bodies lying on the ground were actually stark naked street derelicts, who were "paid" in alcohol.