Casting was complete within two weeks of the start of production. In late November, AB-PT said actress Mala Powers was being considered for the female lead. But on December 2, the studio revealed that Peter Graves and Peggie Castle had been cast as the leads. Three days later, AB-PT announced that Don C. Harvey, Morris Ankrum, Pierre Watkin, Ralph Sanford, and Richard Benedict had also been cast. The studio also said that Pat Dean, its "sexboat" discovery (and a former dancer at the El Rancho Vegas hotel and casino in Las Vegas, Nevada) would also appear in the picture. Larry Blake, Duane Cress, James Douglas, Eileen Jannsen, John Kranston, Ann Loos, and Jeanne Wood were added to the cast a few days later. Ankrum, Henry, and Seay were cast because they usually played military men in B movies, roles they portrayed in "Beginning of the End" as well.