Factual error: Dr Schultz pays with 12 $1000 bills, but $1000 bills were not created until 1861, after the time period of this movie.
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: The evil man request 100,000 pieces of gold for ransom. Each gold piece looks to be about 10 ounces, and 100,000 of those would make the entire thing weigh about 31 tons, but 2 guys are carrying it around in a little chest throughout the movie.
Factual error: After the birth of the baby, James Stewart and "Doc" Witherspoon are discussing the course of the war. "Doc" relates that he has always lived in Virginia and that his son died at Gettysburg at Little Round Top. No Virginia regiments fought at Little Round Top - only Alabama, Texas, Georgia, and Arkansas regiments.
Factual error: In the train scene near the start there are vapor trails from modern day jet aircraft in the sky above. (00:06:15)
Factual error: As the colonel and his companions ride out of Blackthorne, Texas, they pass Saguaro cacti, which, oddly enough, only grow in the Sonora Desert, a far distance from Texas.
Factual error: In the scene just before the fight at the O.K. Corral, Wyatt is talking to his brothers and Doc on the porch of the town marshal's office. There is an American flag flying behind him with 50 stars on it when in fact there were only 38 stars on the flag in 1881.
Factual error: When the posse arrives at the mission, a horizontal jet stream can be seen during this scene. (01:00:00)
Factual error: Approximately 2 hours and 10 minutes into the "restored" full-length video version, there's a birthday party for little Lisa Dickinson, and the Alamo defenders sing "Happy Birthday" to her. The Alamo battle happened in 1836. According to David Ewen's "All the Years of American Popular Music," the song "Happy Birthday to You" was composed and copyrighted by sisters Patty and Mildred J. Hill, first as "Good Morning to All," in 1893.