General Custer was shot in the left breast, not the right breast.
Crazy Horse's war paint is incorrect. He was painted with white hail spots and a red lightening bolt in real life. In this film, his face is painted white with red dots on his face.
Tom Custer is not wearing a red tie. In real life, he wore a red tie like his brother George.
At least 7 of Custer's Officers were wearing Buckskins and Firemen's/Bibbed Shirts, however, only General Custer, Captain Tom Custer, Lt. W.W. Cooke, Lt. Algernon Emory Smith, and Captain Myles Keogh are seen wearing them.
General Custer and a good amount of the Soldiers are wearing suspenders. There is no evidence of this, and General Custer was not known to wear suspenders.
General Custer is seen with a Webley Bulldog Revolver. This is an anachronism, as the actual Bulldog was not made until 1878, however, this was likely a stand in for the harder to find Webley Royal Irish Constabulary Revolver, which George Custer is believed to have carried on him at the Little Bighorn. The term "Bulldog" was also commonly used to refer to short barreled revolvers of the era.
Lt. W.W. Cooke and Captain Tom Custer are seen smoking modern cigarettes in one scene.