When Kearny Called a Bart a Loser His Mouth didn't Move.
When Lisa run out of the front door and told Bart to Shut Up, Her Mouth didn't move.
When Homer rescues Snowball V from the walls, his sleeves are ripped open, but when he sees Santa's Little Helper inside the wall, they are intact.
At the beginning of the sledge race, Ralph was alone on his sledge, but when he passes Bart and Milhouse, there's a snowman with him.