In 1876 the single-shot Springfield Model 45-70 1873 rifle was the standard US Army infantry rifle, as identified by Captain MacClaw when he picks up an abandoned one. The cavalry used a single-shot carbine version of the Springfield 1873. Yet the final battle sequences show both the infantry and the cavalry troopers exclusively using Winchester or Henry style lever action repeating rifles, even though these weapons were never Army issue.
The sergeant says the captain's straps have a black background. As a doctor, the straps would have had a green background. Yellow was the correct color for a cavalry officer. No service had a black background.
The cavalry charge to the rescue of wagons under indian attack. As they near the wagons a 'dead' indian visibly moves out of the way of a horse.