Continuity mistake: As Jesse, Diamondback and Homer try to black out the windows on their car (to protect themselves from the sunlight) Homer spray paints the window next to him black. The camera angle switches to a wide shot as the car drives by. At this time, the back window (which was just blacked out) has not been spray painted yet. It is totally clean again.
Continuity mistake: At the 23-minute mark, instead of two horses tied to the back of the wagon, there is only one. (00:23:00)