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.
Nerdy Crocodile is a parody to Rancid Rabbit