The entire crew had to be still and quiet during the shooting of any scenes involving the Rottweiler dogs.
The film was originally listed (as "Madhouse") as one of the official UK DPP 72 video nasties. It was released fully uncut in 2004.
Producer Ovidio G. Assonitis had to fire and subsequently fill in for the original director who was hired to do this film ten days into the production. However, it was later revealed that the same had happened on Le démon aux tripes (1974), and he would famously do it again with James Cameron on Piranha 2 : Les Tueurs volants (1982). Cameron claimed that Assonitis only hired an American director to get studios to finance his productions; he would then declare that director 'incompetent' just so he could fire them and direct the movie himself.