"Red Zone Cuba" was Francis's final film as director, and his only starring role; in the other two films he helmed, "The Skydivers" and "The Beast of Yucca Flats", he limited his acting to cameos. Though John Carradine receives fourth billing in the credits, and was prominently featured in the advertising and promotional material for the film, he only appears briefly, during a framing sequence at the beginning of the film. Carradine also sings the film's opening theme song, "Night Train to Mundo Fine" (pronounced "Finé"), performed by Ray Gregory and the Melmen.