Some crew members, such as Kenneth Holmes, Dean Henning and John Del Valle and their wives, appeared as 'atmosphere extras' in the film.
Last feature credit for veteran special effects man Theodore Lydecker.
Janice Rule and Ralph Meeker were cast because they were the leads in a New York production of "Picnic", and Republic Pictures' publicity for the movie attempted to exploit the association with Columbia's film version of the play, Picnic (1955). The poster art-work for this film (showing Rule and Meeker) is nearly identical (even using the same muted color-scheme) to that featuring William Holden and Kim Novak in "Picnic".
Tampico and Mazatlan were considered as possible shooting sites.An earthquake resulting in damage to the Colonia Progreso area forced the production team to seek other location sites in the Acapulco area.