Opie falls asleep in the bed of a delivery pickup truck after eating a few apples. The tailgate is down. When the delivery man drives away with the truck, not knowing Opie is in the back, the tailgate is in the up position.
When Andy is sitting on Opie's bed, shots of Andy are reversed. In those shots, Andy's hair is parted on his right side (instead of his left).
While Opie is sitting on the truck tailgate eating apples, there's a possible reflection of a crew member in the house window.
There is a map of Idaho on the wall of the Sheriff's Office, but Mayberry is in North Carolina.