Factual error: When the posse arrives at the mission, a horizontal jet stream can be seen during this scene. (01:00:00)
Factual error: Ulrika is present at the communion in Karl Oskar and Kristina's home, even though she's a Baptist at this point. Not only would she not want to come, or even be welcome since she was now practicing a different form of Christianity, she would not need to come. Being married to the Baptist minister she would be attending communion on a regular basis.
Factual error: The crazy lady, whose family (except the boy), were murdered by Indians, sings "Shall we gather at the river" after Jeremiah buries them. Only that wasn't written until 1864.