Jack Budlong died after falling from his horse onto his sword.
According to 'The Guinness Book of Movie Facts and Feats' a total of 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.
Because of a shortage of native Americans in Hollywood, Warner Bros. imported 16 Sioux from the Dakotas.
The filming of the "Last Stand" sequence from this movie involved some 200 horsemen charging around in pretend battle and was so dangerous that one day during filming Anthony Quinn, who played Crazy Horse, arranged as a gag for a hearse to show up at the filming location
The highest regular Army rank attained by Winfield Scott was actually Major General. Lieutenant General was a brevet (temporary) rank. The First regular Lieutenant General would be Ulysses S. Grant, promoted to the rank in March of 1864. General Scott was also one of three veterans of the War of 1812 still listed in the rolls of the regular Army at the start of the Civil War.
This was the eighth and final film pairing of Errol Flynn with Olivia de Havilland. The last scene they filmed together was Custer's parting with his wife before his final campaign.
To fill the background with "Indians", hundreds of Filipino extras were filmed while the 16 Sioux were used for the close-ups.
Untrained rider George Murphy was killed when he fell from his horse while drunk.