 Finally, Eguiluz changed his mind and helped Naschy find an interested Spanish film producer.In the United States, the film was titled "Frankenstein's Bloody Terror", solely to satisfy the American distributor's need for a second "Frankenstein film" to pad out a planned double feature release.To justify this odd choice of title, an animated opening sequence especially created for the film explained that a branch of the Frankenstein family became cursed with lycanthropy and took the name Wolfstein.