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.
Continuity mistake: In the episode where Henry joins the secret club the newspaper saying that Henry is horrid again has an orange image but when soggy Sid catches them the image is green.
Other mistake: Near the beginning the dividing line in the bathroom has Henry on the right and Peter on the left but as you can see Henry would be on the left due to where his room is and where he would have to walk.
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.
