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 the riders are watching the wagon train, in the background you can see a communication tower with conical speakers.
Revealing mistake: When Howard and Curtin chase Dobbs, they pass a dead donkey which is obviously breathing, and the rope used to tie its legs together is visible too.
Visible crew/equipment: During the movie whenever Bob Hope is pulled off the wagon by his team of horses you can see a board leaning against the wagon that was used to help the stunt man when he was pulled off the wagon.
Continuity mistake: When Sam says to Bugs, "This town ain't big enough for the two of us", Bugs is holding a carrot in his right hand. When Bugs runs out of the saloon in the next shot, the carrot he was holding has disappeared.