When Arnold is in the comic shop two comic books behind him make CatDog.
sticker on poster
Jinta's body guards
Weberman has a CatDog keychain!
Peter is telling Brian that he is a Cat-Dog, which is making fun of calling people who like cats "a cat person". Peter starts talking about the cartoon with Brian and points out some of the cartoon's plot-holes.
Peter says Bryan is a Catdog
Is asked how CatDog uses the bathroom.
Mentioned in dialogue
While in the lava tube in Snow Canyon, a cub scout quotes "CatDog".
The Lucas Bros. become conjoined in one possible future and look like Catdog.
One of the methods by which rabbits reproduce themselves makes them look like the eponmous creature.
Nerdy Crocodile is a parody to Rancid Rabbit