Mine Your Own Business - S1-E4
Other mistake: When Daphne falls down the mine shaft, Fred has turned his head around his body 180°.
Mine Your Own Business - S1-E4
Other mistake: When Daphne asks "What do we do now?", her lips are higher than they should be.
Chosen answer: A ghost wouldn't have to keep any food in the fridge - they don't need to eat. So it is one thing that proves the ghost is not a ghost.