Jane Greer got the female lead, because studio head Howard Hughes didn't want to risk using Jane Russell, RKO's biggest female star, in case the public would turn against Robert Mitchum, because of his jail sentence for smoking marijuana. Greer and Hughes previously had a relationship, which she broke off to get married. Out of spite, Hughes stopped giving her roles, but decided that in this case she was perfect for this seemingly thankless role.
Jane Greer was pregnant during the shoot, but didn't want anyone to know. Seeing her use her pills against morning sickness, co-star William Bendix asked what they were for. After she told him they were for combating "Montezuma's Revenge", he asked her for some. Later, he thanked her because he didn't get sick.