In the episode, Special Delivery, watch how Tommy Pickles goes down the slide after he shakes the stamp off of his hand and dumped onto the slide. When he first goes down the slide, he's sliding on his back with his hands and feet in the air. But at the end of the slide where he crashes into the boxes, he's sliding head first with his hands out in front of him. Wasn't he sliding on his back a few seconds ago?