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.
Factual error: During the campaign for election, Tom Sunday's checkered past comes to light, and it is revealed that he served a year in the pen for killing a Senator in New Orleans five years previously. Since the campaign takes place in 1869, that would mean Sunday did his deed during the height of the Civil War, when New Orleans was under martial law. There were no US Senators at the time, since Louisiana was a Confederate State, and since he proved self defense no charges would have been levied.
Factual error: The boys join up with Don Luis for the trip from Abilene, Kansas to Santa Fe, New Mexico, a journey roughly South West. The morning after Tom Sunday's talk with Tyrel, they enjoy a clear morning's ride. With the rising sun shining brightly on the right side of their faces, almost as if they were headed north.