Clark Gable was anxious to do the film because his father had been an oil rigger, and Gable himself had worked on oil rigs in Oklahoma before becoming an actor.
This was the last of three films (after San Francisco (1936) and Test Pilot (1938)) that Clark Gable and Spencer Tracy did together. After this film, Tracy insisted on a clause in his MGM contract that he would receive equal billing with Gable in all future films. While the two remained lifelong friends, they were never again paired together in a movie because MGM wasn't sure how to handle the equal billing.
The only re-teaming of Clark Gable and Claudette Colbert after their Oscar® winning performances in It Happened One Night (1934).