The Farnsworth Parabox

Act I: Satan! You owe me!
While Professor Farnsworth is in the process of almost killing himself with an experiment spectaculary gone bad, Fry is once again trying to invite Leela to go out with him, but she is refusing and claims that she can't join him because of sweaty boot-rash. Shortly afterwards, the Professor calls on the crew to dispose of a box containing the crazy-ass experiment that almost killed him, by throwing it into the Sun itself. He forbids everyone to look into the box for any reason, fuelling the crews curiosity to a critical stage. Hermes chases off the nosy crew members and sets Leela with a gun to guard the box. Fry and Bender mount a serious attempt to seize the box by crawling through the buildings steam tunnels, and indeed manage to aquire it. It is full of junk, because Leela has foreseen the attempt and planted a fake box so she can guard the real box in peace. However, she is eventually overcome with curiosity herself, and when she goes to the coffee dispenser, she lets a coin flip decide wether to look into it or not. The coin says to go ahead, and Leela looks inside - the box is deep, much deeper than a box this size should be, and she falls through it and lands on the floor. Fry comes in, and looks rather different - he has black hair and different clothes. He is followed by Bender, who has a shiny golden finish, the Professor, who has a curious scar on his head, and eventually Leela sees herself enter the room - with red hair and a cup of coffee.

Act II: How did you get by this stylish head-wound?
The other Professor soon realizes what must have happened: the box contains a parallel universe and is a gateway between the two universes. He suspects that the universe where Leela came from is populated by evil twins and sends the different Leela through the gateway with a gun to round up the other inhabitants. She does so, and the two Planet Express crews end up facing each other in the other universe. The original Leela and her twin end up fighting and beat each other unconscious, and both crews agree to seek a violence-free solution. They decide to name the universe where the original Leela came from Universe A, while the other universe is Universe 1. It seems that a key difference between the two universes is that coin flips have different outcomes, which explains why Leela-1 didn't look into the box and got herself coffee instead while Leela-A did take a look. It also accounts for Bender-1's golden finish and the Professor-1's head scar that he inflicted on himself while experimenting to remove his own brain. Professor-1 has hidden the box with Universe A in it until he is convinced their other selves are not evil, so there is no returning for now. Fry-A and Leela-A are astonished to learn that Fry-1 and Leela-1 are a married couple.

The opposite selves soon learn that their other incarnations are not evil and make friends. Meanwhile, the two Frys and Leelas are having dinner at Elzar's Fine Cuisine, and Fry-1 and Leela-1 tell the story how they got together. It turns out that Leela-1 gave Fry-1 a chance for a date after a coin flip, the date was most satisfactory and one thing led to another. The same coin flip had an opposite outcome in Universe A, so Leela-A and Fry-A didn't come together - Fry-A berates an embarassed Leela-A for her constant deception. The two Zoidbergs hang out in a dumpster (Zoidberg-1 has a blue carapace) and work out a plan to get everyone's attention: to steal the box with Universe-A in it. Both Professors then announce that neither crew is evil, and the crew-A is free to go. Just that moment, Hermes-1 (blond hair) enters and wonders why the crew is not out to destroy the Professor's box. It turns out that Professor-A instructed Hermes-A to destroy the box, so there is no time to lose.

Act III: Hermes, don't press that button!
Professor-1 dives into his personal fishtank to retrieve the box with Universe-A in it, but finds it has been stolen - the Zoidbergs have it. The two Professors decide to take desperate measures and produce further parallel universes in the hope that Universe-A will be among them. Dozens of identical boxes are produced by some strange machine, and the crews try to find the proper universe in them. As they are unsuccesful and about to despair, the Zoidbergs enter with the right box, but flee into one of the boxes as the crews give chase. The other universe boxes fall down around the box, making it impossible to determine which one is the right. The crew members attach themselves to Universe-1 by ropes and explore the boxes that contain weird variations of the Universe, eventually they seize the Zoidbergs and obtain the box with Universe-A in it. They all return to Universe-1 and then rush into Universe-A to stop Hermes from disposing the box into the sun - they arrive just in the moment when Hermes is about to release the box out of the ship, and he can be persuaded not to kill everyone as he has them at his mercy.

The crews make their farewells, and Leela-A decides to give Fry a chance and lets herself be invited to a big ape fight. The Professors grab the other universes box and pull - and end up with a box containing their own universe. Quite a responsibility, really. The crew adjourn to the TV, and Fry takes a seat on the box, compressing the screen slightly... No one seems to notice anything's changed.

Trivia

 * If all of the universes are parallel, at least a few of the parallel characters, Robot Fry, Ancient Rome Profesor, Bobblehead Bender etc., would also be looking for the other versions of Zoidberg, but they're not.
 * One of the planets seen in the zoom-in scene of the Universe-A box to Universe-1 is Planet Eternium.
 * Leela is reading a magazine, the Nosy Inquirer, headline: Bigfoot turns 80!
 * The Planet Express Ship has aquired an Ejection Port, large enough for PE crews A and 1 to easily fit into it.
 * The Planet Express building in Universe-1 is blue, and the sky has a strange colour pattern.
 * The Futurama game, developed around the same time as this episode was written, depicts Bogad as being in a corner of the universe. This fits well with the universe-in-a-box concept.
 * Shortly after the professor A comes into Universe 1 He declares that he made a Parallel Universe; Professor 1 then states: "Baldurcrap, I created your Universe! All you created was my fist Parallel to your face." Then Professor 1 punches Professor A, invalidating Professor 1's statement (hitting him makes his fist perpendicular to Professor A's face- parallel lines do not intersect).
 * This episode was named #17 on IGN's list of Top 25 Futurama Episodes.

Parallel Universes
A description of the universes explored by Crew-A and Crew-1:
 * Universe A - The normal Futurama universe. Boxes in this universe are yellow.
 * Universe 1 - The first alternate universe seen, coin tosses have opposite outcomes and almost everything is a different color. Boxes in this universe are blue.
 * Universe 25 - Nobody has eyes. Boxes in this universe are white.
 * Universe 1729 - Everybody is a bobblehead version of themselves. Boxes in this universe are pink. It is possible that 1729 was intentionally chosen to represent this universe by the Futurama writers, because 1729 is the Hardy-Ramanujan number.
 * Universe 31 - Everybody is a robot version of themselves, and robots may possibly be human, although none are ever seen. Boxes in this universe are green.
 * Universe XVII - The overall outfit of this universe matches the Roman Empire. Boxes in this universe are purple.
 * Universe 420 - A hippie universe where marijuana smoking is implied both by its smoky haze and its label 420. There appears to be a shortage of boxes in this universe. Boxes in this universe are orange. 420 is commonly used slang for smoking weed.
 * Other universes - One (explored by Fry) is very cold, another (explored by the Professor) has everyone as women, a third sticks on Hermes-1's head, and another (explored by Leela) has octopus residents. Also, both Benders steal treasure from both a leprechaun universe and a pirate universe.

Quotes

 * Hermes-A: Here Leela, take this (laser pistol) and use it to shoot those guys. Leela-A: Right! If they try to look in the box. Hermes-A: Whatever.
 * Hermes-A: Like Granny said: if you want a box hurled into the sun, you got to do it yourself. God rest her zombie bones...
 * Leela-1: (referring to Leela-A) We're exactly the same! I know all her moves, therefore I have the upper hand!
 * Bender-1: It's like I said: Make new friends but keep the old, one is silver... Bender-A:... and the other's gold! (They hug and cry)
 * Leela-A: Uh, have you robot-versions of you guys seen any extra Zoidbergs around here? Robot Fry: Negative! Will. You. Go. Out. With. Me? Leela-A: Uh, access denied. (Robot Fry's head explodes)
 * Hermes-1: Sweet Honeybee of Infinity!
 * Bender-1: (gold-plated)Hey! Bite my glorious golden ass!
 * Leela-1: The idiots have the box! Dr. Zoidberg-A: ''(referring to Dr. Zoidberg-1) I think she means you.
 * Prof. Farnsworth-420: (in a hippie-like universe) Dig it! All you fitting in this box is like seriously freaked up. Prof. Farnsworth-1: Non-sense, wha, there's a whole universe in there. Prof. Farnsworth-420: Dude, there's a universe in all of us. (Trying to give Prof. Farnsworth-A a flower) Prof. Farnsworth-A: ...Get a job!

Characters

 * Fry
 * Leela
 * Bender
 * Professor Farnsworth
 * Hermes
 * Zoidberg
 * Amy
 * Narrator
 * Fry-1
 * Leela-1
 * Bender-1
 * Professor-1
 * Hermes-1
 * Zoidberg-1
 * Amy-1
 * Professor-XVII
 * Fry-25
 * Hermes-25
 * Leela-25
 * Professor-31
 * Fry-31
 * Hermes-31
 * Professor-420
 * Amy-420
 * Fry-1729
 * Bender-1729
 * Leela-1729

Episode Credits

 * Writer
 * Bill Odenkirk
 * Director
 * Ron Hughart
 * Voice Actors
 * Billy West
 * Katey Sagal
 * John DiMaggio
 * Phil LaMarr
 * Lauren Tom
 * DVD Commentary
 * Matt Groening
 * David X. Cohen
 * Bill Odenkirk
 * Ron Hughart
 * Billy West
 * Maurice LaMarche