Opie Steps Up in Class - S8-E5
Continuity mistake: When Aunt Bee picks up Opie at Billy's house, she parks the car in front and walks up to the front door. In the wideshot there's a space of approximately 3-4 feet between the blue window shutter and the door trim under the pediment, but in Aunt Bee's closeup there is no space whatsoever.
Opie Steps Up in Class - S8-E5
Continuity mistake: When Aunt Bee drives up to the Hollander house with Opie, in the wideshot the car's rearview mirror is affixed to the windshield, but in the closeup the mirror has vanished.
Answer: Those "boxes" are valences that used to be very common, before air conditioning. They allow for windows to be open during rain storms. They permit air circulation, without letting the rain in.