In the book, "Garfield At 25: In Dogs Years I'd Be Dead", Jim Davis stated that this is his favorite of the Garfield TV specials.
The voice of the unscrupulous hotel clerk is provided by Frank Nelson, who played a similar, smarmy character on Jack Benny's radio and TV show. The clerk greets Jon Arbuckle with Nelson's signature line from the show, "Yeeeeeeeeeeesss?" When Jon asks for the hotel's cheapest room, the clerk says, "Oh, that would be the Jack Benny Suite." (This is also a reference to Benny playing a notoriously cheap character on radio/TV)
"The Cruiser" is clearly modeled after James Dean.
The ancient tribe Garfield, Odie and Jon encounter used to listen to Phil Harris records. This is another reference to Jack Benny. Harris was the bandleader on Benny's radio show.
During the opening title sequence, when Garfield imagines himself to be a Hawaiian singer, his lips move when he speaks/sings.