When the anvil falls on the Polar Bear's head he takes right hand to cover his mouth so he won't wake up the Bulldog but in the next shot when he is writing ouch! his left hand is covering his mouth.
When the anvil falls on the Polar Bear's head he uses his right hand to cover his mouth to keep the Bulldog from waking up, but in the next shot when he rights down ouch! his left hand is covering his mouth.