It was reported that Clark Gable, who described himself as 6'2", wore lifts to look taller than his 6'4" co-star Robert Ryan in several scenes. Gable also stood on a box to look taller than Ryan when they first see the jayhawkers.
Most of the long shots of Clark Gable were actually a double.
Robert Ryan became ill with hepatitis and had to leave the production for two weeks.
Clark Gable was never on location for the Montana scenes.