Continuity mistake: When John gets into his friend's van after he leaves the retirement home, they show his bald spot. While he gets out of the van, the spot completely disappears. When they show him from behind, walking towards the house in the next shot, the bald spot is back again.
Continuity mistake: When John is on Tyra, right after he gets up off the couch they show him and Maggie arguing in the kitchen. You see John hit Maggie's coffee out of her hand and we see some splash on her. After John leaves and Maggie sits in front of the camera on the couch, there is no sign of coffee anywhere on her.
Other mistake: When Beverly Farley asks her son, John, where he has, she states that she thought John was going to ride together with her and Mr. Woodcock, to the awards ceremony. But later, when she leaves the ceremony she is mad in her own car, and Mr. Woodcock's car is right next to the awning. So Beverly and Mr. Woodcock did not drive there together. (01:00:20 - 01:06:10)
Audio problem: During the corn eating contest, the original loud metallic clang of an empty bucket was used over and over, even as the buckets filled up and the sound would have become muted.