Gorillas are central characters in the film. These giant primates can not be trained to be used in film, so the filmmakers employed the skills of master prop maker Stan Winston. Winston, used the combination of an actor in a gorilla suit and a headpiece that was intricately designed and controlled using sophisticated technology. The focal point of the film is the bond created between an anthropologist and the gorillas he lived with for several years. In one scene, live gorillas were filmed at the Los Angeles Zoo. AHA did not provide on-set oversight for the techno-primates, however we were present when live animals were filmed.