In Up, Carl is frustrated by Kevin the bird and Dug the dog (Bob Peterson) following him, so he throws one of the tennis balls from the bottom of his walker into the jungle for Dug to chase after. Then he throws a piece of chocolate for Kevin to chase. He and Russell walk away, ditching the two animals. It turns out that the jungle Dug runs into is the exact same background as one that appears in Cars 2.
The scene happens when Mater is watching the Mel Dorado Show. It’s a story on the oil billionaire Sir Miles Axlerod (Eddie Izzard) and his journey to become the first car to ever circumnavigate the globe. Ironically, he runs out of gas and becomes stranded, emerging from the jungle a month later, running on a fuel created from jungle forage. A clever kid noticed the similarity.
Pixar is known for leaving Easter eggs in their movies that connect its films — leading fans to come up with an elaborate theory that all of the studio’s feature films belong in the same universe — but the connection between Up and Cars 2 seems like it could have simply been a cost-cutting trick. It is far from the first recycled animation scene, something the older Disney films did as a matter of course.