Luigi Montefiori, aka George Eastman, who co-wrote, co-produced, and portrayed the disfigured cannibalistic serial killer Klaus Wortmann stated that when he went to the premier at the old Cinema Metropolitan in Rome with the producer, only a few people were in the theater watching. During the film people kept walking out until only a single couple remained. Later, during the scene where the pregnant woman was strangled and had her fetus ripped out of her, the couple got up and walked out offended. (In real life the effect was achieved using a skinned rabbit, and was something new and very disturbing for the time.) Montefiori and the producer ended up the only ones left watching the rest of the film.
Tisa Farrow's voice is dubbed by another actress in the English language version.
This was the very first film reviewed by Joe Bob Briggs for the Dallas Times-Herald.
As of June 12, 2015 this film has passed uncut with an '18' certificate for "Strong gory violence and horror" under the title 'The Savage Island.'
According to Joe D'Amato, some of the heads and bones in the catacombs were plastic imitations. Upon collecting them after the scenes had been shot, the crew accidentally took with them some real bones. Since D'Amato did not dare to return them, he let them make a "pilgrimage" to his house.