Revealing mistake: Doyle is making a chair in woodwork, but as he is fitting one of the legs he hits the chair with a hammer too hard and splits the wood then gets a telling off from Mr Hopwood, the wood was already split before Doyle hit it.
Episode #3.1 - S3-E1
Revealing mistake: Karen Stanton supposedly hits Michael Doyle in his nether region with her satchel but she actually hits him below the knees.