This is the only movie in which Paul Naschy plays a wolf man who is not Waldemar Daninsky. He detested the script so he didn't want his beloved character in it. The wolf man in this film is just known as "El Hombre Lobo" (The Wolf Man) or "H.L."
The LP also appeared in 1982, it included 12 songs (6 from the movie in side A, and 6 new songs on the B side). In the movie side there was the song "Doce campanadas" which doesn't appear in the movie. This was the last Regaliz's LP.