Factual error: After the first encounter with the Apaches, the covered wagon is headed to the Fort at full speed. The camera pans to the Apaches on the ridge and you can see a truck driving at the bottom right corner. (00:32:00)
Factual error: When York is explaining to Thursday about Cochise and the Indian agent's calumny, he states that Cochise took his people off the reservation, and crossed the Rio Grande into Mexico. The reservation in question would have been in the Arizona Territory, and the Rio Grande ceases to be the international border at El Paso, Texas. Cochise may have gone into Mexico, but he didn't cross the Rio Grande to get there.