One of the dogs in the pack is a Basset Hound. In the final scene in which the dogs are seen together, the Basset is nowhere to be seen.
When Andy, Barney and Opie leave the courthouse to retrieve the dogs, it's storming. When they return, their clothes and the dogs are dry.
At the point in which Barney puts the dogs into the squad car on the passenger side, he turns toward the rear of the car to walk around to the driver's side. But, as the camera angle changes to the driver's side, Barney is coming around the front of the car.
It was established in "High Noon in Mayberry" that the mail would be officially delivered through the front door mail slot, yet Barney brings in the day's mail from outside.