Custer is shot too far down on his side. In real life, he was shot in the side of the left breast, right above the heart.
General Custer is seen wearing the blue army pants. He wore buckskin pants in real life.
General Custer was likely using a Webley Royal Irish Constabulary Revolver, not a Colt Single Action Army Revolver like he is shown using in the film.
Custer had roughly 100 men on Last Stand Hill, not 30.
The soldiers on Last Stand Hill shot their horses to use for cover, but there are none shown in the film.