Audio problem: When we see the can-can dancers perform on-stage, the music is played by a full band including brass and drums, despite the fact that there's only a pianist on-stage. (00:22:10)
Suggested correction: This error is not unique to Carry On Cowboy. It seems that in very many western movies (and TV shows) there might be a scene in a saloon, in which a singer or some dancers are performing on a stage. In nearly all such occasions they seem to be accompanied by a full orchestra which is nowhere to be seen.
This is not a valid correction. To say the error exist in other films does not invalidate this error.
Sorry, I think I got that wrong. I was not trying to invalidate the error, far from it! What I meant to say was that I agree that this is quite an obvious error in Carry On Cowboy, and that this also seems to be a common, and rather amusing, error in many other western films as well.
Unfortunately at this time, valid mistake entries are not subject to forum discussion where one agrees or discusses the mistake. Just give the mistake a thumbs up if you agree with it.
Other mistake: In the very last scene of the movie, and just before Blondie shoots the rope that is holding Tuco on the grave's cross. You can see a car moving in the background, screen right of Tuco's head.
Continuity mistake: In the final scene at the sheriff's office, Mitchum has his feet up on the table top, and the boot soles are clean. But after Wayne walks out, there is suddenly a spot on a boot sole. (This is visible in the video)
Revealing mistake: As Jango fires the machine gun, the ammunition chain hanging from it is loaded on both sides, and it doesn't move. Also the belt has different sizes of cartridges in it. (00:45:30)
Deliberate mistake: When Raza is chasing the "empty" train, as it goes over the trestle just before he stops it, you can see the engineer in the train's engine.
Revealing mistake: In the last scene, when Chris is leaving, it shows several shots of the peaceful village. Each time they show the village, in the middle of the square is what looks like two boys fighting. One punches the other and he falls down and gets up and punches back and he falls down. They do that about three times.