During the climax, Sheriff Chappy shoots nine shots out of his revolver without reloading.
After signing for the money at the bank, Harry and Wayne walk along the street looking for a car to steal. The first car on the corner is a 4-door Volvo Sedan. Wayne tries the door and it is locked so they move along to the next car. The shot changes to the next car and in the background you can see a man open the door of a domestic pick-up truck where the Volvo was in the last shot.
The hotdog that Jo was eating at the auction.
There are no mountains or vineyards anywhere near Happy, Texas.
Happy is said to be in southwestern Texas near El Paso. In fact, the real Happy is in the northern part of the state between Amarillo and Lubbock.