Most of the supporting roles were played by a professional cast, including, notably, Rod Taylor, along with G. D. Spradlin, in one of his early feature film roles, following many appearances on U.S. national television. Paul Fix, a friend and acting coach of John Wayne who had appeared in many of Wayne's films, played the owner of a roadhouse in the Mojave desert. Kathleen Cleaver, a member of the Black Panthers and wife of Eldridge Cleaver, appeared in the documentary-like student meeting scene at the opening of the film.