Marge comes through the door and you see that she has come from a room with a piano in it. It has a music book on it. But when the shot changes so we see Marge turn the jar upside down, the music book has disappeared.
When Homer walks out Circus of Values with his purchases, he bumps into Flanders, and all the presents scatter everywhere. Watch out for a red present with a green bow that goes flying near the left hand side of the screen. As soon as it hits the ground it turns into a pink box with a white bow wrapped around it, with no shot changes.