When Morgan sets Jennie free, she takes his revolver and then falls from the cliff, taking his revolver with her. In subsequent shots, however, Morgan has a pistol again.
In the final battle scene, there are three Indians charging the position. The Indian in the middle has his own reins, plus the reins of the rider on the left of screen. This is before they are fired at. Then, as the left-hand rider is shot, hangs on but then falls into the river, the central rider pulls his horse straight.
The "dead" Arapahoe takes a lungful of air.