When Foghorn Leghorn sets up the rocking chair next to the hole, he places a board under one of the legs of the chair.
The next shot shows the chair several inches away from the board.
When Rhode Island Red is shown leaving thru the gate, there is a large knothole in the fence, but as he walks away you don't see him visibly thru the knot hole.
When Foghorn Leghorn says "Something, I say, something went wrong", his beak doesn't move.