Lisa says that Michael Jackson and Dustin Hoffman were voice actors in The Itchy & Scratchy Movie, and that "they didn't use their real names, but you could tell it was them". This was reference to the fact that Jackson and Hoffman have contributed to Simpsons episodes under the respective pseudonyms of John Jay Smith and Sam Etic.
In the scene of forty years into the future, the picture of Bart and caption "DO NOT SELL TO THIS BOY" are still posted in the box office at the Aztec Theater.
Another cartoon is Itchy and Scratchy (Tom and Jerry version) in army background.
The 50-year old Bart Simpson; Chief Justice of The Supreme Court, and the 76-year old Homer Simpson; senior citizen coming into the theater sitting down in the shadows for the movie to begin is an homage to Mystery Science Theater 3000 as Mike Reiss has mentioned on the DVD audio commentary. Thank you for your idea, Joel Hodgson!
Itchy and Scratchy the Movie is the parody of Tom and Jerry the Movie.
Homer's remark about Soylent Green 40 years in the future (which would have been 2032) is a direct reference to the sci-fi thriller "Soylent Green", which is about a mysterious new addictive food-like substance. The film is famous for its twist ending, in which one character remarks "Soylent Green is PEOPLE!".