The cast member who had the hardest time with John Ford was John Agar, making his film debut. Whether it was because Agar was newly married to Ford's beloved Shirley Temple or because he wanted to test him, the director rode him mercilessly, calling him "Mr. Temple" in front of everyone, criticizing the way he delivered lines, chastising him for his lack of expert horsemanship. One day Agar stormed off, vowing to quit the picture, but John Wayne took him aside and helped him with some of the more difficult aspects of his job.
Although John Ford would not allow wives and girlfriends onto his locations, John Wayne was allowed to bring his son Michael Wayne with him to Monument Valley. He later described the rugged conditions and the long, six-days-per-week working hours: "The only thing people could do in Monument Valley was work; there was no other diversion. But the rougher it was, the more Ford seemed to like it."
George O'Brien, an old friend of John Ford's who had starred in his silent Il cavallo d'acciaio (1924), came out of retirement to play the fort commander replaced by Henry Fonda in this story.
John Agar never forgot the generous and patient help John Wayne gave him as an inexperienced young actor on this production. "I would go to hell and back for Duke," he later said. They worked on five more films together.
The opening music sequence contains a few bars of "She Wore a Yellow Ribbon." This was the theme music for the film of the same name, the second of John Ford's "Cavalry Trilogy".