During the meeting with the lawyers about the divorce, Mrs. Farmer mentions that July is seven months away, meaning it is December. Yet, in the next exterior shot we see the grass is green and the leaves are still on the trees.
Andy's wet clothes cause two continuity errors. First, when he falls in the water as the boat leaves the dock at the picnic, he is fully dry when seen shortly after fishing in the boat. Second, on the way home from the picnic he is sopping wet as they stop at the kennel, but fully dry as they arrive home with the Irish setter.
As Andy and and Michael Sinclair are trying to disable Crum Petree's pickup truck with the boulder, Andy attempts to conceal Michael with brush (leaves, twigs, branches). The amount of brush covering Michael changes between shots.
At one point, Andy gets annoyed with the bird singing right outside his window, and throws hot coffee at it. The bird nest is not right outside Andy's window. An earlier shot from the nest shows it to be too far away to hit with coffee.