Like Cannibal Holocaust (1980), this movie contains several actual animal killings. Though his character kills an animal in the film, Giovanni Lombardo Radice strongly objected to the animal killings and refused to participate in them (a double had to be used). Director Umberto Lenzi tried to convince Radice to do the killings by telling him, "De Niro [Robert De Niro] would do it," to which Radice responded, "De Niro would kick your ass all the way back to Rome."
Although the tag line for the initial USA release was "They raped and killed his sister while he watched helplessly. Now it's his turn to Make Them Die Slowly," nothing like this happens in the film.
(at around 30 mins) When filming the death of the wild boar, Giovanni Lombardo Radice nearly severed the hand of his double. Although Radice refused to kill the pig himself, a shot of Radice slashing the knife downward was needed to show that his character killed the pig. (The shots of the pig's death were later spliced in between.) To create blood splatter for this shot, Radice's double, who actually killed the pig for the film, was to hold a bowl of fake blood, which Radice would then stab. However, the double held the bowl from the bottom, and when Radice stabbed the bowl, the knife went through and cut his double's hand badly. Because of this accident, Radice saw himself as possibly "avenging" the pig's death.
Advertisements still claim that the movie is banned in 31 countries, even though several countries have lifted the ban since it was first printed.
Giovanni Lombardo Radice used the stage name John Morghen to make audiences think Cannibal Ferox was more of an Americanized movie rather than an "obscure foreign film".