The script for the voice work was to be kept so secret that the producers personally shredded the script after every voicing session.
In the original script, Marge was going to be the one to have the vision in church. However, as Marge is normally very reserved and rational, the crew felt it would make more sense for the family to overlook the warning if it was delivered by Grandpa instead.
For the entire month of July 2007, as part of a campaign to hype the July 27th opening of the movie, twelve "7-Eleven" stores all over North America changed their names to Kwik-E-Marts, and begun selling products like Buzz Cola, KrustyO's cereal, Radioactive Man comics, and Squishees, including WooHoo! Blue Vanilla flavor. One store in Burbank, California reported selling over 57,000 sprinkled donuts matching the one featured in the movie poster. Only one of the twelve locations was in Canada, located in Coquitlam, British Columbia (a suburb near Vancouver).
(at around 47 minutes) When the Simpsons arrive in Alaska, the border guard gives them $1,000 in exchange for the mining of Alaska's natural resources. This actually happens in real life, though a citizen has to reside there for at least twelve months first. The Alaska Permanent Fund, which is funded by oil production and revenue from other sources, pays out an annual dividend to every eligible Alaskan resident. When it began in 1982, Alaskans were paid $1,000. The amount varies from year to year based on the growth of the fund.
Edward Norton originally recorded the part of the man who gets crushed by the dome using a Woody Allen impression, but the crew felt the voice was too distracting, so Dan Castellaneta re-recorded the dialogue with a different voice.