Factual error: The town of El Dorado is located in Texas, as evidenced by the Texas county map on the wall in the County Sheriff's office. However, while on their journey to the town, Thornton and Mississippi shoot at Saugaro Cact, which is only found in the Sonoran Desert in what was then Arizona Territory.
Suggested correction: Wayne has expressly stated earlier that he is heading to Sonora. He is returning from Sonora at this time.