The movie was filmed during the summer 1987. Was registered in 1988 (according the credits copyright), but never had a theatrical premiere. According with Spanish diary ABC of October 17 1989, the movie would be projected on Munich Fantastic Film Festival that month. The movie had the TV premiere at dawn of August 16 to 17 1991.
The movie that the kid is watching when he gets scolded for watching his father's movies is from another Paul Naschy film, 'Panic Beats'... Original title: 'Latidos de Pánico' from 1983.
According to Spanish diary ABC of February 26 1987, announcing the beginning of the filming (which finally was delayed until the summer of that year), says that the movie 'is written by Hermes Omaña and Salvador Sáinz'.
According with Salvador Sáinz's letter to the director in the same diary of August 31 1991, the script was written by him, and later Paul Naschy redacted the second version of it and modified some things. They agreed to sign the script together, Naschy under the pseudonym of Hermes Omaña, but when Naschy restart the filming during the summer 1987, didn't notify Sáinz about it, and registered the script under his own name. The only name which appears as a writer in the movie credits is Paul Naschy's name.
Paul Naschy's real life son, Sergio Molina, played his character Hector's nephew Adrián.
Paul Naschy plays 8 characters in the movie: Héctor Doriani, Alex Doriani, Frankenstein's Monster, Mr. Hyde, Phantom of the Opera, Waldemar Daninsky the Werewolf, Quasimodo and The Devil. Some sources incorrectly add 3 more characters, Rasputin, Bluebeard and Fu Manchu, but actually, that characters were the character of Héctor Doriani characterized as that characters, without intention in the movie of make believe that actually were that characters.