Continuity mistake: When Kevin Costner gets hit on the head by the top frame of the door, he is knocked out unconscious. Yet, when he gets back up after regaining consciousness, the blood from is head had been running down his nose. Don't you think that as he was lying down in a horizontal position, the blood would run down over the eyes towards the ears?
Continuity mistake: At the close of the buffalo hunt, Wind in his Hair cuts out the liver of the buffalo, holding it in two hands. He stands to take a bite out of it and it's already about half its previous size. When he hands it to John Dunbar, it shrinks dramatically in size again, and is a different colour and shape.
Visible crew/equipment: In the scene where the Sioux discover the rotting dead buffalo lying in the valley, as they are riding by them, right after they show a Sioux woman crying, in the background you can see a man with dark hair in a white shirt lying on the ground. In the special edition DVD, if you watch this scene with the commentary on you will hear Kevin Costner and Jim Wilson admit that it is an assistant cameraman trying to get out of the scene.
Continuity mistake: When Kicking Bird is trying to steal Cisco and Dunbar frightens him away, he falls over the fence. He scares his horse, who runs off to his right. But then Kicking Bird jumps up and runs to his left, and suddenly his horse is waiting for him there, standing still.
Revealing mistake: At the end of the movie, just before Dunbar arrives at the winter camp in the mountains, after being rescued by Wind in his Hair and his men, an old Indian man looks up and see them coming down the mountain. The old man is wearing thermal underwear under his leather tunic.
Factual error: When Lt. Dunbar gets to the Fort, they show a dove in the rafters. It is a domestic Ringed Turtle-Dove or domesticated Barbary (African Collared) Dove. They likely did not have those doves at the Fort, but rather should have been a Mourning Dove. Rock Doves and chickens were common domestic animals brought for food.
Continuity mistake: After Dunbar and Timmons have arrived at Fort Sedgewick and they realize everyone is gone, after Dunbar says "Not at the moment, we don't know what happened," the shots of Timmons alternate from having no egg on his face to having a lot egg on his face, especially on the tip of his nose.