Revealing mistake: In the opening credits, Beefy Bert has a different hair colour to what he has in the actual episodes. This was not included in Series 3.
Revealing mistake: Gordon is shown to have a lisp but when he opens his mouth we can see that he has front teeth.
Suggested correction: Not all lisps are caused by missing front teeth or a gap in the teeth. A dental lisp is caused when the tongue is pushed against the front teeth. Lisps can also be caused by other forms of tongue misplacement.