Continuity mistake: When Daniel Day Lewis, his brother and father are going after the Munro girls and the officer, in one scene where the dark haired Munro girl falls against a bush and breaks the branches. If you look closely at the scene before, the branches are already broken.
Continuity mistake: When the Huron chief is talking and Duncan is translating, he is translating faster than the chief can talk. (01:27:00)
Continuity mistake: When Uncas single-handedly attacks Magua's party on the mountain, he shoots an opponent who is filmed falling off the side of the mountain. When the camera cuts back to the fight, you can see him fall down again on the far left (while Uncas is attacking the next one in line).