Continuity mistake: When the gang of bad guys ride to the ranch there are nine of them. When they leave, and throughout the rest of the movie there are only seven, despite only one being shot off his horse at the ranch. (00:15:15)
Factual error: When the trappers first encounter the Rickarees, the bow cannon is discharged, creating an explosion near the Indians, who promptly turn and ride away. Immediately after, a second shell explodes near them. It would be impossible for a single gunner to sponge out and reload with cartridge and ball in the space of 10 seconds.
Revealing mistake: A 'bald wig' is visible on Harry Morgan when he first arrives in Purgatory.
Factual error: Raquel Welch is shown to have modern tooth fillings during the rape scene.