Gable and Davis instead of Mitchum and Parker
The original leads in the film were supposed to have been Clark Gable and Bette Davis. However, due to Gable's untimely passing in November 1960, Robert Mitchum was cast instead.
I think it worked better with the next generation as opposed to the fifteen or so years difference between Gable and Mitchum.
This is one of my favorite Robert Mitchum roles. His own personality fits Captain Wade Hunnicutt just perfectly. Mitchum never fully got the recognition he deserved. He should have been nominated for an Oscar for this role. He only got one nod, and that was in the Supporting Actor category in 1945's "The Story of GI Joe", only to lose to a well deserved recipient, James Dunn ("A Tree Grows in Brooklyn").