The operatic version of "Spider-Pig" (which plays over Homer's epiphany scene, and again over the end credits) was released as a single in England and fell just shy of the Top 20.
As inspiration for the crowd scene in the film, the production staff spent a long time looking at the Simpsons poster that features over 320 of the show's characters. Groening said that they did try to put every single character into the film, with 98 having speaking parts.
When Lenny is on the phone with Homer about the donut shop going out of business, the donut Lenny is holding is the donut from the movie's promotional material.
The season 4 episode "Kamp Krusty" was originally going to be a film, but difficulties were encountered in writing a movie length script, at which point the movie plans were dropped in favor of a season premiere.
The script was re-written one hundred times, continuing after animation had begun. This meant that "two films' worth" of finished material was cut, including cameos from Isla Fisher, Minnie Driver, Erin Brockovich, and Kelsey Grammer.
The film was shipped to theaters under the fictional title "Yellow Harvest." This is a reference to "Blue Harvest," the fictional working title of Return of the Jedi.