Factual error: The action in this movie takes place in 1869, yet half of the handguns are 1873 Colt Peacemakers, and the remainder that are Army or Navy Colts are all cartridge conversions, which were not available until 1871.
Factual error: After Tell Sackett shoots the first Bigelow, he departs Uvalde, which is in Texas, and heads for the hills. He encounters a trapper, and over coffee, they discuss lost gold. The trapper indicates that earlier seekers had perished, some from exposure, some from Crow Indians. However, Santa Fe, where Tell goes to resupply, is over five hundred miles from normal Crow haunts. Far more likely to be Utes, Comanches, or even Apaches.
Factual error: When Ty and Sunday face off, Ty plants a .44 in Sunday's breast pocket. However, as he presents the Colt, it is obvious that there are no cartridges in the weapon, no bullet noses are visible in any of the chambers.