[[caption-width-right:350:Going by this promotional picture, you'd almost swear this was an EnemyMine between Bob & Bart.]]

Bart fears his new neighbor might be Sideshow Bob -- and his suspicions send The Simpsons into a bizarre case of mistaken identity.

!! Tropes:

* AlliterativeName: Walt Warren.
* ArsonMurderAndJaywalking: When Walt shows the Simpson family Bob's room, a lot of pictures of Bart and Krusty with knives pinned in them are shown, as the words are inscribed "Kill Bart!", "Kill Bart!", "Kill Krusty Too!" and "Buy Milk!"
* CassandraTruth: Bart believes that Walt Warren is Sideshow Bob just based off his voice. He's right and he's almost killed because he believed that he was wrong.
** Walt Warren himself. He was set up to look like Sideshow Bob and he had a difficult time telling people who he really was. He even tried warning Bart that he was going to die, but people obviously didn't believe him.
* CelebrityParadox: PlayedForLaughs with Marge and Homer assuring Bart that lots of people sound like Sideshow Bob: Frasier from Series/{{Cheers}}, [[CriticalResearchFailure Frasier]] from Series/{{Frasier}} and Lt. Commander Tom Dodge. Guess who voice these characters.
* ComicallyMissingThePoint: Homer failed to realize tacos are called tacos in both English and Spanish.
* DuctTapeForEverything: As Sideshow Bob explains his GrandTheftMe of Walt, he uses excessive duct tape all over the place to tie Bart to a car chair and gag his mouth; as Bart tries signalling Bob to remove the tape, he puts more duct tape on his already taped mouth.
* EatTheCamera: Ends the first act, when Bart runs screaming from "Walt" among recognizing the voice as Sideshow Bob, he runs right into the camera, his mouth turning the frame black.
* HiddenDepths: Even though he's a minor offender, Walt managed to perfectly plan and execute his escape from prison, which could mean that either there's more criminal behavior in Walt's past than has been revealed thus far, or that while he and Sideshow Bob were cellmates, Bob bragged about his exploits enough for Walt to pick up a few pointers.
* JurisdictionFriction: {{Averted|Trope}}. While Sideshow Bob is at Five Corners (a place where five states meet) by the time Chief Wiggum finds him, police officers from the other states show up to arrest Bob and his only choice is where he'll be arrested.
* NoodleIncident: The waitress laments that every man she flirts with is either gay or has no face. Now, the "has no face" part was shown, but the gay part wasn't.
* OffOnATechnicality: Bob's plan to kill Bart was shooting from a state while his gun-holding hand was at a second state; having the bullet cross another one; having Bart being hit in a fourth state and falling dead in the fifth. No single action could be prosecuted or so Bob believes. Even he seems to realize it doesn't make sense since he just decides to shoot Bart when he keeps jumping and says that if anyone asks he followed his plan.
* PapaWolf: When Walt wearing Bob's face shows up to warn Homer and Marge, Marge sprays water in his mouth and Homer slams the windowsill on his neck making it clear he is gonna kill him this time.
-->'''Homer:''' Alright buddy, I'm gonna do to you what you should have done to my son a long time ago.
* ParrotExpowhat: When Bart recognizes "Walt's" voice and screams, "Aaaah! Sideshow Bob!", "Walt" pretends not to understand and asks, "Side-what Whom?"
* PhotoshopFilterOfEvil: As Bob starts discussing his murder plan to Bart, the picture goes to some sort of color/black-and-white negative filter, indicating the future action of the plan detailed in slow-motion.
* PoliceAreUseless: Subverted. Bart called Wiggum and had him follow Bob's car using a tracking device. Police officers from other states [[WhereTheHellIsSpringfield (Texas, Minnesota, New Jersey, and one unidentified)]] also show up to prevent Bob from killing anyone in a different state.
* PoorCommunicationKills: Almost. "Bart Simpson will die" was a warning, not a threat. When Marge points out Walt's poor choice of words, he sheepishly responds "I'm not a writer".
* RakeTake: Happens when Bob tries following Bart through all five corners of each state in an attempt to kill him... and accidentally steps on a rake that appears out of nowhere, a CallBack to "[[Recap/TheSimpsonsS5E2CapeFeare Cape Feare]]".
* ShoutOut: Bob said his plan to kill Bart would be the greatest murder ever since [[Literature/HarryPotterAndTheHalfBloodPrince Snape killed Dumbledore]].
** Bob's plan hinges on ''Film/FaceOff''-esque surgery.
** Walt Warren sounds like Creator/JimmyStewart.
* SouthOfTheBorder: Falling for Walt's look, a waitress misleads the Simpsons into going to Mexico.
* SubvertedSuspicionAesop: After spending half the episode trying to prove that Walt was really Bob, Bart eventually decides he was wrong and even takes him up on his offer to go a trip. It's only after he gets in the car does he find he was right and that he really ''is'' Bob.