The Rover Hendrix joke (where the veterinarian, when Homer sarcastically asks if he has any more messages for Jimi Hendrix, tells him to tell Hendrix to pick up his puppy, which is a dog with a blue bandana lying in a sixties decorated bed) was criticized as being one of the worst Simpsons jokes in history.
Lisa eats bacon for breakfast, 19 episodes after she announced she is a vegetarian.
Despite Mr. Burns' complete lack of knowledge of the modern world and technology, he somehow knows what Ticketmaster is.
The song the Smashing Pumpkins play Is "zero"
Homer's first cannonball stunt on the Hullapalooza tour is a near frame-by-frame replica of footage of Frank "Cannonball" Richards, a vaudevillian of the 1930s, performing the same stunt.
During Peter Frampton's concert, Mr. Burns mentions that Smithers used to laugh at his decision to buy ticketmaster, as "no one would pay a 100% service charge."
The scene where young Homer approaches the guys at the van is inspired by the 1993 film Dazed and Confused. One of the guys resembles Matthew McConaughey's character Wooderson, while another resembles Rory Cochrane's character Ron Slater.
"Homerpalooza" is a parody of Lollapalooza, an annual rock festival.
Otto Mann's talking shoes in Otto's hallucination spoke opening line from Prince's 1999.
After the first time Homer gets struck by a cannonball, the ball disappears in the next shot.
After dodging the cannonball, Homer is wearing a helmet, goggles, blue shorts and tennis shoes, but when he steps off the stage, the helmet and goggles disappear and he is wearing his blue flannel pants and his gray shoes.
At the end when the Pumpkins walk away, during the wideshot they are completely different people.
Homer doesn't know popular music such as Nine Inch Nails yet it is revealed in "that 90's show" he created Grunge music. I realize that Obviously it wouldn't be known that the Simpsons would extend past the 90's for homer to be in college then, just worth pointing out.