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.
Although this episode centers largely on Bea's death, at the end of the episode when Abraham announces it is time for dinner in the new Beatrice Simmons Memorial Dining Hall and the residents file in, a woman who looks just like Bea can be seen among them. Maybe it's her ghost again...
Bea's hair is gray but it turns blue during the scene when she and Grampa are dancing.
Grandpa states he only has one son to Bea but just two episodes before he revealed to Homer he has another son, Herbert Powell.