Most of the "Native Americans" in this movie were portrayed by Hispanic or Caucasian actors, because there was a noticeable lack of Native American actors at MGM at the time this movie was made in 1950.
When the original version of the finished film was submitted to MGM executives, they didn't like it. The film went through heavy editing, and a producer had the idea of tying together the surviving pieces by adding voice-over narration from Mitchell's grown up son, as if he is telling his father's life story. Howard Keel, who had just finished making Show Boat (1951), was brought in for this purpose. The changes led to director William A. Wellman effectively disowning the film. When asked about it in an interview, he said "I've not seen it, and I never will."
During filming Ricardo Montalban was thrown from a horse and trampled. The resulting injury to his spine left him in constant pain for the rest of his life which increased as he aged, eventually leading to a 9-1/2 hour operation in 1993 in an unsuccessful attempt to correct the damage. The operation left him paralyzed from the waist down.
Uncredited Stuntman, Jack N. Young, who had doubled for Clark Gable in several movies as they were look-a-likes, was requested by Gable to be his double on this movie. Gable asked Mr. Young if he would do his stunts without credit as it was billed Gable was doing his own stunts. Mr. Young graciously told Mr. Gable that was fine. Mr. Young could see that Mr. Gable was ill and would not be able to do his own stunts as he had in the past. The admiration for each other was never more apparent than this conversation between the two men.
Lon Chaney Jr was up for the part eventually played by James Whitmore. Whitmore was cast because he was under contract to MGM and it was cheaper to hire contract players as opposed to Chaney who was a freelance actor.