Two scenes where deleted from the final cut of the film. One of them was after Chaco leaves the group for dead, an injured Clem crawls on his wounded leg and unties Stubby. This scene was deleted because it dragged the film on. Despite the fact the scene was deleted it was seen on one of the lobby cards issued for the film. The other scene omitted from the film was a full blown love scene between Stubby and Bunny, but it was deleted because it was considered excess. To this day the scenes are considered lost or have yet to be discovered.
Director Lucio Fulci clashed with screenwriter Ennio De Concini over the script. Disliking what Concini wrote, Fulci took it upon himself to rewrite the entire screenplay.
Lynne Frederick (Bunny) and Fabio Testi (Stubby) were smitten with each other during filming, naturally helping their chemistry in the movie. In the aftermath of Frederick's blacklisting in Hollywood, Testi is one of the few people who continues to publicly speak fondly of her.