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.
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.
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.
Continuity mistake: When Bugs says "Gin! You lose!" at the end of the card game, he is wearing a cowboy hat and gun holster, but when we see Bugs in the next shot, the hat and holster have gone.