As Bass walks across the country for weeks his facial hair doesn't change.
Van Dorn is portrayed as an older man, but he was in his early 40s at the battle of Pea Ridge.
George Reeves is portrayed as on old man, played by actor Shea Wiggam, who is in his mid 50s. In reality, George Reeves was 36 at the time of the battle.
The cards used in poker game that Reeves plays his master for his freedom had numbers on them. During this time period cards did NOT have numbers on them, just the number of symbols of their suits (ie, 6 of clubs just had 6 clubs and had NO number 6). Numbers would come later in the 19th Century.
In the scene at the river, Bass and Curtis don't understand each other, but in the next scene, they communicate without a problem.