The book did not have enough material to fill the run time, so the cartoon added the quest for the Moss-Covered Three-Handled Family Gradunza, and the list of the Cat's identities in foreign countries, to flesh out the story.
This is the first Dr. Seuss television special to use the 1971-1975 Cat in the Hat Productions logo and it's extended with two parts in this special.
In this short, the fish is named Carlos K. Krinklebine. In the book and in The Cat in the Hat (2003), he is unnamed.
This special has been released on home video by both Paramount and Universal. These studios share the rights to The Cat in the Hat (2003), Paramount having inherited their share of the rights from DreamWorks.