Abraham and Beatrice crossing each other's arms while taking their medicine is similar to a scene in the film Tom Jones.
When the Discount Lion Safari employee scares away the lions with a shotgun, he is clearly familiar with the reputation Homer has earned, as he says "Mr. Simpson, I presume?", akin to the famous statement "Dr. Livingstone, I presume?"
Once Grampa acquires the fez from Herman's Military Antiques, he is seen wearing it for the remainder of the episode.
Darth Vader and The Joker can be seen waiting in line as candidates for Grampa donating his money.
When Grampa takes a walk to clear his head after interviewing candidates for the money, one of the places he visits is a reference to Edward Hopper's Nighthawkspainting.
This is the only episode of The Simpsons that has the voice actors and the characters they play credited simultaneously.
In the casino, Grandpa recites the first four lines of the third stanza and the final two lines of the fourth and final stanza of the poem "If--" by Rudyard Kipling
Bea's hair is gray but it turns blue during the scene when she and Grampa are dancing.