Benny guesses that the door set high in the wall was out there to confuse ghosts. This is likely a reference to the Winchester Mystery House in San Jose, California. Mrs. Winchester believed strongly in ghosts and had numerous tricks and traps for them built into her home.
Moral for Winner Winner: Tilly learned she's a champion no matter what.
Moral for Harvest Dinner: Cricket and Gramma learned even the most mundane of jobs are very important.