The children of Springfield wage war on Shelbyville after their beloved lemon tree is stolen from them by Shelbyville children. The parents of the Springfield children take Ned's recreational vehicle to search for their boys, and when they find them, the children convince them to help recover the stolen tree from an impound lot.
- All There in the Manual: Bart's counterpart has No Name Given in the episode, but the official episode guide identifies him as Shelby.
- Angry Fist-Shake: When Homer steals Flanders's RV away from the impound lot, the lot's owner (an Expy of Homer) and his son Shelby (an Expy of Bart) shake their fists at the fleeing Springfieldianites.Shelbyville Homer: Ooh, you lousy Springfielders, you - shake harder, boy!
- Bait and Switch: When Bart is being chased by a guard dog, Homer attempts to distract it by throwing a steak its way, but instead, the dog swallows it whole while still chasing after Bart, leading Homer to exclaim, "Faster, son! He has a taste for meat now!"
- Bluff the Impostor:Shelbyville Kid: If you're from Shelbyville, how come we've never seen you at school?
Bart: Uh, I don't go to school.
Kid: OK... what's 2 + 2?
Kid: Eh, his story checks out.
- Brick Joke: Shelbyville's split with Springfield over marrying cousins saves Bart, when he's surrounded by the Shelbyville kids and distracts them by shouting "Look, someone's attractive cousin!".
- Buffy Speak: Shelby's father: "Get out here, son. There's a doin's a-transpiring!"
- ...But He Sounds Handsome: While infiltrating Shelby's gang, Bart hears them talking about the Springfield kids trying to get the tree back, and responds with "Curse those handsome devils!"
- Butt-Monkey: Flanders suffers the most in this episode. First, Homer forces him to use his RV to drive Springfield's fathers around Shelbyville to find the boys, it suffers damage for the whole ordeal, and he's the one who gets saddled with the impound fee at the end (though he is able to easily afford it).
- Chameleon Camouflage: Milhouse has an Imagine Spot that while wearing camouflage he blends into the bushes completely.
- Chekhov's Classroom: Subverted. Early in the episode, Ms. Krabappel is teaching Roman numerals, which would come in handy for Bart later when he is trapped in the Shelbyville zoo and finds himself in front of several doors marked with Roman numerals, only one of which - the one marked seven - is the exit and all the others have tigers on the other side - except that he didn't pay any attention and figures out what seven is in Roman numerals in a completely unrelated way (by using the Rocky films as reference).
- Chekhov's Gun: Defied.Bart: "I could sure use that flying motorcycle now."(Frink flies by on it)Frink: "You had your chance!"
- Comically Missing the Point: When Bart rushes out of the house, declaring he's going to "teach some kids a lesson". Marge declares she's going to take it literally, and later believes Bart actually has a tutoring job.
- Continuity Nod: Shelbyville residents drink Fudd Beer, the brand mentioned in "Colonel Homer".
- Evil Gloating: Homer's Shelbyville counterpart mocks him, refusing to return the lemon tree, and decides to eat one in front of them, puckering his face up.
- Faith–Heel Turn: Lampshaded when Bart is handing out roles to the members of his team. He designates Todd Flanders "the quiet religious guy who ends up going crazy".
- Five-Man Band:
- Flashback... Back... Back...: Marge repeats the last line of a lecture on civic pride she gives to Bart: "Sorry to repeat myself, but it'll help you remember." Sure enough, Bart later has a flashback to what she said, and remarks, "Hey, that does work!"
- Incest Is Relative: The cause for the town rivalry between Springfield and Shelbyville is due to Jebediah Springfield falling out with Shelbyville Manhattan, when the latter expressed a desire to marry his cousins in the town they would found together:Jebediah Springfield: Why would we wanna marry our cousins?
Shelbyville Manhattan: Cause they're so attractive. (confused) I— I thought that was the whole point of this journey!
Jebediah Springfield: Absolutely not!
- Lost Common Knowledge: Bart has an Imagine Spot where people from the future bring him back to life (by shooting a ray gun at a piece of graffiti he's made). He wows them by taking out a yo-yo.Man 1: What's normal to him amazes us.
Man 2: He will be our new god.
- Malaproper:Homer and Bart: Eat my shorts, Shelbyville! Eat! My! Shorts!
Ned: Yes, eat all of our shirts!
- Mirror Universe / Similar Squad: Shelbyville is a full-on copy of Springfield, with counterparts to many of its major citizens and points of interest. Bart and his friends all had Shelbyville counterparts who are antagonistic to our heroes. However, Milhouse and his counterpart managed to become friends.Milhouse 2: But Milhouse is my name!
Milhouse: But I thought I was the only one!
- My Car Hates Me: When the Springfielders need to escape from the Shelbyville impound lot, Flanders is unable to start the RV. Turns out Homer was draining the battery by cooking roast chicken.
- Mythology Gag: Shelby's dad is voiced by Hank Azaria doing a Walter Matthau impression, just as early Homer was voiced by Dan Castellaneta doing a Matthau impression.
- Namesake Gag: Shelbyville is named after founder Shelbyville Manhattan.
- Nice Job Breaking It, Hero!: If Marge hadn't given her speech about Springfield's civic pride to Bart and the rest of the family, he and the rest of the boys might not have snuck into Shelbyville to get the lemon tree back.Marge: This is my fault. I tried to teach Bart about town pride, but the power of my words filled him with a sort of madness.
- Non-Indicative Name: The Shelbyville newspaper, the Shelbyville Daily is printed once a week.
- No Time to Explain: Parodied. Nelson bursts into the classroom and shouts "Everybody, come quick! Something's happened. No time to explain." Along the way, he stops to take a drink at a fountain, and is asked if it wouldn't be simpler to explain the matter. His response is, "No! I said there's no time to explain and I stick by that!"
- Not So Great Escape: Bart tries to escape the Shelbyville kids by using spray cans as a jet pack. It fails miserably, so Bart just makes a run for it.
- No, You:Bart: Hey! Stop talking bad about my town, man.
Shelby: Why don't you make me?
Bart: I don't make trash, I burn it.
Shelby: Then I guess you're a garbage man.
Bart: Well, I know you are, but what am I?
Shelby: A garbage man.
Bart: I know you are, but what am I?
Shelby: A garbage man.
Bart: I know you are, but what am I?
Shelby: A garbage man.
Bart: Takes one to know one!
Shelby: [Gapes in surprise]
- Reading Lips:Milhouse: What are they saying?
Bart: I'm not sure.
Milhouse: I thought you said you could read lips.
Bart: I assumed that I could.
- Ridiculous Future Sequelisation: Rocky VII: Adrian's Revenge (though a seventh Rocky movie would come true, it was a spin-off focusing on Apollo Creed's son, aptly titled Creed).
- The Rival: Bart has Shelby (a doppelganger from a rival town, Shelbyville) as a rival. In fact, Milhouse also has a rivalry with his own counterpart (also named Milhouse) from the same town.
- Skewed Priorities: Homer gets the boneheaded idea to start a barbecue in the middle of making their escape from the impound lot.
- Silly Reason for War: Previous episodes have shown that the rivalry between the two towns has been violent at times; as Lisa explains, Springfield built a mini-mall that was purposely larger than a mini-mall Shelbyville built. Then, after Shelbyville made the world's largest pizza, Springfield burned down their city hall. Then Shelbyville spiked Springfield's water supply to get even. And on, and on, and on. Supposedly, this all started because of an argument over the right for men to marry their cousins.
- Small Town Rivalry
- Stock Object Colors: When Bart's expedition reaches into Shelbyville, they marvel at how much like Springfield it is, except for small details. Milhouse in particular is spooked by the fact that the fire hydrants are yellow instead of red.
- Trojan Horse: Homer and the others park Ned Flanders' RV in front of a hospital and wait for it to be hauled away. After the plan works, Homer comments that no one in history has ever had such a brilliant idea.
- Vitriolic Best Buds: Nelson and Martin, sort of. Nelson makes it clear he can't stand Martin, but still sheepishly saves him from one of the Shelbyville kids (though not before explaining he wouldn't normally).