During the opening scene in the living room, there are a bottle and a glass on the table next to Andy that disappear between shots.
Aunt Bee gets an apple from Opie's room and there is no bite out of it, but when she comes into the kitchen, there is a bite taken from the apple.
When Aunt Bee arrives home to a perfectly clean house, she comments that it's better than she could've done herself. Keeping in mind how small Mayberry is, the bus stop can't be more than a few minutes away, perhaps 15 minutes for a round trip, and Bertha would have had only a few minutes to clean the house. A large, 2-story house like that would take one person several hours to thoroughly clean.