Factual error: When you walk into the courthouse the first jailhouse to the left has a window. But the courthouse is connected to another establishment on that side. A window would be impossible.
Factual error: The badges they wear don't match the badges on their patches. If there's a badge on the patch, it's supposed to match their actual badge.
Factual error: A town like Mayberry with a mayor and council would have its own police force, not just a sheriff.
Factual error: December 25, 1960 was on Sunday. The calendar in the jail house shows a calendar (which has been used in other episodes) with Christmas Day on a Friday. (01:30:00)
Factual error: Andy tells the hobo "that will be the 3:45 stopping for water", meaning its a steam locomotive, but by the time this episode was made railroads had long since switched to diesel.
Andy and Barney in the Big City - S2-E25
Factual error: Though they are suppose to be in Raleigh, the skyline view is not Raleigh, NC.
Factual error: We know from 2 episodes prior (Man in a Hurry) and generally mentioned throughout the show, the only filling station in Mayberry is Wally's Filling Station. In this episode Mayor Stoner is accused of only putting the new underpass in Mayberry because it will be next to Mayor Stoner's brother's filling station.
A Black Day for Mayberry - S4-E7
Factual error: An armored truck is going to Fort Knox from Denver would never go through Mayberry. Fort Knox is in Western KY south of Louisville on I-65. NC is accessible mainly by going south down I-75 to Knoxville, then heading South East along I-40 towards Asheville, NC. To get to NC from Fort Knox you would need to go up to Lexington then Knoxville/or go east across the wky fka The Green River pkwy to I-75 then to Asheville. There is no easy route; why would they go through KY to NC and turn back to KY?
Goober Takes a Car Apart - S5-E17
Factual error: Halfway through the show, Goober takes the motor out of the car and they start it up in the Sheriff's office. If you look at the direction of the fan, it would be blowing the air forward instead of towards the rear of the engine. It would be fighting the air coming through the radiator instead of pulling it.
Goober Takes a Car Apart - S5-E17
Factual error: How in the world did Goober lift that heavy motor out of the car?
The Gypsies - S6-E23
Factual error: The Gypsies manage to operate a shortwave radio without an antenna or AC power.
Goober Goes to an Auto Show - S8-E22
Factual error: Goober and the Taylors stop and get gas in Raleigh before heading back to Mayberry. As they are waiting, a Coors Brewing Company truck is seen driving past the service station. Coors Beer was not sold east of the Mississippi River until the mid-1980s.
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.