This, along with other Pixar shorts and commercials, appears for a millisecond as Hamm is rapidly surfing channels so they can find the Al's Toy Barn commercial.
When the fish tank turns dirty, they show a shot of a sunken ship. On the front of the sunken ship is the mermaid from Pixar's ''Knick Knack'' covered in scum.
The snowman can be seen in the snow globe in Lizzie's shop when Lightning is helping all the denizens of Radiator Springs. Also - during the final showdown race - plastic flamingos can be seen near some of the RVs, like the "Sunny Florida" knick knacks.