Revealing mistake: In the early part of the chase scene, when the person hanging the banner swings into the pane of glass, you can actually see it start to shatter before he touches it.
Revealing mistake: When Stan is in the safari park driving the bus with the monkey on the steering wheel the scene outside the bus is obviously background projection and at times it runs backwards giving the impression that the bus is in reverse when all the time it is going forwards.
Revealing mistake: When Bernard Bresslaw punches the guard who is grabbing hold of his girlfriend during the fight at the market, you can see that his fist never makes any contact with the guard's face.
Revealing mistake: When Hattie Jacques and Barbara Windsor see Madeline Smith about her baby, you can see that the 'baby' is an obvious doll.
Revealing mistake: When the cafe owner takes Mike's chef hat away from him to continue frying the food on the hot plate, he stands on Mike's hand and breaks an egg. You can see that the egg is a fake one as no yolk is visible.