Somewhere over the Brain-bow is the Part 1 of Futruama Simpsons Infinitely Secret Crisis.
The comic begins in Springfield, with a mayoral election between current mayor Joe Quimby and Snowball II, the Simpsons' cat. It turns out that this is in fact an old edition of Simpsons Comics, which Fry is reading as the Planet Express crew head to the living planet of Nerdanus XII. They are taking the biggest comic collection in the universe to the planet, where it will be sealed in liquid diamond forever, as this is apparently the only way they will be collectibles.
While unloading the comics, the crew are hit by the Brain Spawn's stupifaction ray, which drastically decreases any living being or robot's intelligence. Fry, however, is the only being in the universe unaffected, due to his lack of a delta brain wave. Fry, by throwing objects at the Brains, manages to make Leela and Bender intelligent again, but the crew are then trapped inside various comics and adverts by the Brains.
Bender manages to use a spoiler ray to force the Brains to reveal their plan. The Brains plan to take over the Earth by creating a false collector's market - by sealing comics up, they will no longer be able to be read. They will then do the same with films, books, paintings and other art, until the collective intelligence of Earth's inhabitants is low enough for them to invade. Fry says that the rest of the Planet Express crew would avenge their deaths, so Professor Farnsworth, Hermes, Amy, Scruffy and Dr. Zoidberg are brought to the planet. Another remark by Fry gets the crew, plus Nibbler, trapped inside an old Simpsons Comic, the one Fry had been reading earlier.
Apart from Fry and Nibbler, the crew get amnesia and wander off into the world of Springfield. After Nibbler realises that they would be more likely to find the main characters (i.e., the Simpsons), Fry sets out to find them.
Bender goes into Moe's (to celebrate his new found sobriety) and meets up with Homer Simpson, who assumes that he's the new Duff beer mascot. Fry heads to Springfield Elementary, where after being mistaken as the new sub teacher, he becomes the teacher of Bart Simpson's class. He tries telling Bart of his origins, but naturally Bart does not believe him and has him locked in the school at the end of the day. Leela sees Lisa Simpson being bullied by classmates and helps her stand up for herself. Hermes and Zoidberg end up at the power plant, where they attract the attention of Mr. Burns and Smithers. Scruffy also becomes assistant groundkeeper at one point and argues with Groundskeeper Willie. Marge Simpson mistakes Nibbler for a baby (due to him hypnostising her) and gives him milk, which causes him to lose his memory as well. And Farnsworth is arrested by the police after they think he's insane.