Caillou hosts the "Which one doesn't belong?" game at the end of the episode. In a group of a carrot, a tomato, lettuce and a toothbrush, the toothbrush doesn't belong because it's not a vegetable. A ferryboat is the odd one out in a group that also includes a car, a van and a truck --- the others all travel on land. In a set of a swingset, a flower, a slide and a mechanical horsey, the flower is a plant, whereas the others are things to play on.