Continuity mistake: Sacajawea (Donna Reed) dives into the water to retrieve some important maps, which have fallen in and been taken to the back of the boat. When she dives in, the maps are back to the original area they fell into, when they should have been quite a distance from where they landed in the water.
Continuity mistake: During the ambush on the river two Indian braves can be seen firing arrows one gets shot and dies but the brave who is left his hair and clothing are wet. The scene cuts away and when it cuts back to this brave he stands up only to get shot in the heart. He clutches his heart with both hands and then dies by falling into the river but now his clothes and hair are completely dry. It's clear that the earlier part was a retake after he fell in the river.
