Jim Thorpe, who was an extra, had an off-camera fight with Errol Flynn. With one punch Thorpe knocked out Flynn, who was in his Custer uniform.
Because of new union laws, producers were forced to use regular screen extras without stunt experience. During the first days of shooting, 80 were injured and three were killed. The filming of the Last Stand sequence involved some 200 horsemen charging around in pretend battle and was so dangerous that one day Anthony Quinn, who played Crazy Horse, arranged as a gag for a hearse to show up at the filming location.
To fill the background with "Indians", hundreds of Filipino extras were filmed while the 16 Sioux were used for the close-ups.
According to "The Guinness Book of Movie Facts and Feats", three men were killed during the cavalry charge scene. Bill Mead's horse tripped while riding alongside Errol Flynn. As he was going down, the stuntman had the presence of mind to throw his sword forward to avoid it, but bad luck caused the hilt to get stuck in the ground and Mead fell on it, impaling himself.
The US government did not keep its treaty with Chief Crazy Horse or his people.