The joke about Homer's voice not matching the file from 1989 is because 'Dan Castellaneta' (Homer) uses a different voice from the one in the first season.
Mr Burns says, "I never want to see the word 'Yale' again. We're changing all of our locks to Schlage." Yale and Schlage are competing manufacturers of door locks however he could be referring to the Yale lock company and not Yale University.
The sign behind the baseball announcer reads, "Enjoy Your Last Game, Vin Scully Impersonator." Vin Scully, the long-time broadcaster for the Los Angeles Dodgers, retired in 2016.
Dan Castellaneta and Jason Alexander were both co-starred in Aladdin's second film, The Return of Jafar (1994). Dan Castellaneta also provides uses the voice impersonating of Robin Williams since he was voiced as Genie in the second film.