When Erin and Chad are in the pond, Chad's wet hair changes between shots.
At 2:07, the shadows of the film crew can be seen on the side of John-Boy's car as he drives off.
When Erin and Chad are saying goodbye at the pond you can clearly hear a jet flying overhead. As this is set around 1935 jet aircraft did not exist.
John Boy tells Chad that his great-grandfather settled Walton's Mountain in the 1700s. As established in numerous other episodes, John Boy is referring to Rome Walton, who settled the mountain in 1789. However, Rome was actually John Boy's great-great-grandfather. John Boy's great-grandfather was Samuel Walton (son of Rome Walton, and father of Zebulon Walton).