The Itchy & Scratchy short at the beginning is a work of genius! Even more so than the one featured in "Itchy & Scratchy: The Movie", which was simply a TV Itchy & Scratchy short made to seem like it would be shown in a theater.
This little moment as Lenny and Carl are discussing plans to take out the bomb:
Lenny(to Carl): But who'd be dumb enough to stay behind while we escape with our lives?
(Cletus walks in, carrying possum)
Cletus(clears throat): Mah time t' shine!
When the mob breaks into the house, Krusty orders Mr Teeny to take out Maggie, who responds by breaking a bottle and daring him to come at her. The monkey immediately runs away scared and they try leaving her alone after that.
After the Simpsons escapes the dome, Lisa and Colin have a heartfelt goodbye... until Bart comes up behind her and taunts "Lisa's got a boyfriend, that she'll never see again!" in a mocking sing-song voice. She socks him.
At the convenience store, Bart vandalizes a "Wanted!" Poster of his family behind the cashier to avoid being recognized, and at the same time, a family with the exact same features added by Bart arrives and is apprehended.
Homer, a relatively overweight (admittedly Acrofatic) man, punching out a soldier with one hit. Given how he's often shown to be a bit of a wimp and coward, it's quite impressive. Especially since his family is in danger.
Martin totally beats up the bullies with a plank in just one swing.
Homer and Bart riding a motorcycle on the dome to stop the bomb, which even has a Call-Back to "Bart the Daredevil", as they successfully jump Springfield Gorge. There is possible symbolism there, in that the show has finally, finally crossed over into film. Note the double Call-Back in this scene when, after they jump the gorge, the ambulance that crashed after trying to rescue Homer from the gorge in that episode IS STILL THERE.
At one point, it looks like they'll fail to jump the gorge again, only for Bart to use his slingshot to catch one of the out-hanging rocks, and letting the recoil pull them back up. Farfetched? Yes. Awesome? DEFINITELY!
Bart sums it up best afterwards:
Bart: Now that was a great father-son activity. (Homer nods in agreement)
Maggie knocking out Russ Cargill with a rock.
You have to admit, it took some gumption for Homer to climb the wall of the dome with his superglue-covered hands.
Homer riding the truck and sliding on the snow up to the door.
The Curtain Call credits, proudly showing just how many of the show's beloved characters are played by only a handful of actors. Harry Shearer has no fewer than twelve characters under his name!
Quimby: This is SERIOUS, people! No more dumping in the lake!! I hereby declare a state of emergency: code black!
And as feeble as his preventive measure was, Quimby did get concrete barriers installed around the lake (along with multiple signs prohibiting any further dumping) and had them tested to ensure that everyone follows the same mindset as both his and Lisa's; even the Springfield Mafia willingly agreed to the police's demands never to dump at the lake to avoid further trouble. A very rare moment of competency from a character who defines incompetent mayors. Unfortunately for both Quimby and Lisa, Homer refused to get the message.
Eventually after most of the town's resources are depleted, everyone in Springfield snaps and launches an assault against the dome in an attempt to break it. While most of their attempts are hilariously pitiful such as Ralph using a bubble wand and Krusty throwing pies at it, Stampy the elephant manages to cause a tiny crack in the dome. Although this sets up the upcoming conflict, props to everyone for trying and proving it is possible to break it.
