Homer's rant about deceased celebrities "appearing in commercials dancing with vacuum cleaners" is a reference to a 1997 TV advertisement that depicted the late Fred Astaire dancing with a Dirt Devil vacuum cleaner.
Apu's sandcastle is a very detailed replica of India's famous Taj Mahal.
When Springfield shows up to see Alec Baldwin and Kim Basinger, Comic Book Guy mentions the caterpillar drive from The Hunt for Red October, and says that he has come up with a list of technical errors he thinks Baldwin would enjoy to discuss.
In one scene, Homer prank calls Gloria Stuart which he describes as the "old lady from Titanic'' to tell her she stinks.
Homer ranted about never seeing Ray Bolger (known as the actor who played The Scarecrow in the 1939 film The Wizard of Oz). Bolger died in 1987, which is why no one has seen him in a while.