Marge claims that the government doesn't listen to everyone's conversations, but is proven wrong when she gets heard by a robot clone of the train conductor (while they were riding the train between Alaska to Seattle train station) used by the National Surveillance Agency to spy on people's conversations. Director David Silverman said that unlike the TV series where "you [have] to pick and choose", the film gave them the opportunity to "lavish that attention [on] every single scene". He dumps the silo into the wonderfully clean lake, causing it to become heavily polluted almost instantly. A 1½-minute-long trailer was then shown on November 12, 2006, immediately after the second act of The Simpsons episode " G.

They put down their rock instruments and take out violins, as Green Day bassist Mike Dirnt, saying that "it's been an honor playing with you tonight", begins to play "Nearer, My God to Thee" (from Titanic) alongside his band mates as the barge sinks and kills them. After an encounter with an Inuit shaman who saves him from a polar bear, Homer has an epiphany about saving the town to save himself.

Groening read about a town that had to get rid of pig feces in their water supply, which inspired the plot of the film. While the character animation is about the same as a normal episode from the later seasons, there are visual elements that have gotten an upgrade. The Monthly critic Luke Davies echoed Lowry's concerns about the length: "everything moves with the whip-crack speed of a half-hour episode.

Meanwhile, while Lisa is trying to get signatures for a petition to clean up Lake Springfield as nobody wants to talk to her. Regarding the scene where the tenants of Moe's Tavern and the Church switch locations, he believed it took the "chance to unmask everyone's human fallibility.When they pull his body apart, Homer realizes that he cannot survive without others, and must save Springfield and his family. As a result, the entire townspeople focus their efforts on cleaning Lake Springfield and installing barriers to prevent anyone from dumping anything into the lake. After a three-season run, the sketch was developed into a half-hour prime-time show that was an early hit for Fox.

Cargill, now mad with power, is determined to keep anyone from getting out of the dome and to get the Simpsons back in.

Homer showing Marge the silo in the back yard in the storyboard included on The Complete Ninth Season DVD.

When Lisa's tactic convinces many, Moe tells the town that they hate young kids, but Mayor Quimby finally gets to Lisa's point and forbids any more dumping, declaring a state of emergency. It was the eighth-highest-grossing film worldwide and the tenth-highest grossing in the United States of 2007. Realizing that Springfield is in danger, all of them decide to save it, except for Homer, who refuses to help the people who tried to kill them. Phil Villarreal believed that there were "too few laugh-worthy moments" and that "instead of stretching to new frontiers, the film rests on the familiar".Richard Corliss of Time said that the film "doesn't try to be ruder or kinkier, just bigger and better". Homer Simpson sitting on his couch in a Superman t-shirt and briefs in the teaser trailer that debuted on March 31, 2006. Another dropped scene featured Moe describing Springfield's varying physical states inside the dome, one of which was the Disneyland ride Autopia. Fox held a competition between 16 Springfields across USA to host the American premiere, with Springfield, Vermont being selected as the winner. Storyboard artist Martin Archer was credited for devising the way to cover Bart's genitals with different things before they are exposed to the viewer.