Airdate: September 27, 2009
When Stewie enters a genetically engineered pig at the carnival, Brian asks him where it came from. Stewie reveals to Brian that with an interdimensional teleporter, he can travel to different universes and takes Brian to a universe without religion, where everything is 1,000 years advanced, where he just bought the pig. After exploring that universe, Brian asks if Stewie can take him to other universes and he agrees. First, they stop at a Flintstones-esque universe, followed by a universe where America never bombed Japan in World War II, making the world dominated by Japan. Later, they travel to a universe where everyone has two heads, one happy and one sad, followed by a universe where they are trapped in a second Ice Age, where Brian helps them escape.
After going to a universe where "everyone has to poop right just now", they go into a universe where everything is run by Disney. They're happy with staying there until the inhabitants attack Mort the Jew. They then go to a Robot Chicken universe, followed by a universe where the U.S. botched the Cuban Missile Crisis and the world is in World War III, then a universe with everyone animated poorly. The universe traveling continues with stops at universes of fire hydrants, homosexuals, live-action, political cartoons, a guy who yells compliments from afar and misleading portraiture. They finally stop at a universe where the roles of dogs and humans are reversed. Brian wants to stay to Stewie's chagrin and a fight for the traveling remote causes them to drop it and break, leaving them with no way back home.
In the dog universe, they decide to go the Griffin house, with dog versions of the family and a human version of Brian. The two hide after Stewie bites Dog!Peter and "human control" is called upon. Dog!Stewie gives them his traveling remote, but wanting to live in a man-dominated world, Human!Brian stows away with them. This time, they make it back home and Human!Brian wishes Stewie and Brian goodbye before getting run over.
"Road to the Multiverse" contains examples of (YMMV goes here):
- Alternate History: Some of the universes, like the Japan-dominated universe and the World War III universe.
- Alternate Universe: Brian and Stewie visit many alternate universes in this episode, including one where they are seen in live-action.
- And I Must Scream: While not taken seriously, Stewie and Brian are still conscious while they are in a block of ice.
- Animation Bump: The Disney sequence.
- Art Shift: Many, from the Disney-esque animation to stop-motion and even into live-action.
- Artistic License Religion: Played for Laughs. The Sistine Chapel still exists in the ultra-advanced no-Christianity universe; the ceiling was just decorated by John Hinckley, Jr., who covered it with pictures of Jodie Foster.
- Author Tract: Outgrown Such Silly Superstitions. In the first alternate universe visited, "Christianity never existed, which means the dark ages of scientific repression never occurred, and thus, humanity is a thousand years more advanced." It's not as bad as the entirety of "Not All Dogs Go to Heaven" or even the end of "Family Goy" where Jesus Himself tells Peter that all religion is crap (with Brian yelling, "Thank you!") in terms of religion-bashing, but it will leave a bad taste in some viewers' mouths.
- Brick Joke: Stewie removes Brian's poop in the futuristic universe and tells him it goes to another universe. Later, when the two are trapped in an iceberg, Stewie notices the poop.
- Butt-Monkey: Meg. Even in the futuristic alternate universe, where she's smoking hot, she's still considered ugly compared to Lois (Stewie says, "If you saw Lois you'd have to put your penis in a wheelchair." On DVD, the line is, "If you saw Lois your penis would shoot right off your body.") Of note, and probably obvious to many, this universe's Lois doesn't appear.
- Crapsaccharine World: The Disneyverse. It's a fun and cheerful place where everyone gets along, and even when Herbert (as the hag from Snow White) tries to spoil the fun, he is defeated in a comical way. Stewie honestly can't think of a reason not to stay there... until Mort walks in. The Disneyverse is a magical place... but if you're a Jew, you die.
- Disneyesque: The Disneyverse. This episode provides the page image.
- Elemental Plane: The episode featured quite a few of these.
- Human Popsicle: Stewie and Brian enter a universe where they are completely frozen in a block of ice.
- Look Both Ways: At the end of the episode, Human!Brian promptly gets hit by a car as he crosses the street.
- Male Gaze: There is a slow, upwards panning shot of Sexy Meg in the alternative universe that Brian and Stewie visit.
- Motor MouthDog!Peter: OH-MY-GOD-I-KNOW-THAT-SOUND-IT-MEANS-THERE'S-A-POTENTIAL-INTRUDER-AT-THE-FRONT-DOOR-OR-ONE-OF-MY-PALS-EITHER-WAY-I'M-EXCITED-AND-READY-FOR-ANYTHING!
- Noodle Incident: Apparently, Dog Stewie and Human Brian have had a universe-hopping experience of their own.
- Pet Homosexual: Parodied. Chris wins a "live, genuine homosexual" as a carnival prize.
- Pie in the Face: Herbert (as the hag from Snow White) gets this this treatment from the rest of the characters in the Disney universe.
- Rock Theme Naming: Parodied in the Flintstone universe with Rock-Peter and Rock-Lois.
- One universe is based on The Flintstones (which, coincidentally, was the next cartoon Seth MacFarlane worked on before he put it on hold in favor of The Cleveland Show).
- "Take your stinkin' paws off me, you damn dirty dog!"
- Brian's alternate name in the dog universe is Blake Carrington.
- "I hope this next leap will be the leap home."
- Smurfing: Exaggerated in the Flintstone universe.Brian: Wanna get the rock out of here?Stewie: Rock yeah.
- Slasher Smile: While the rest of the Disneyfied characters look at Mort with sheer malice, the Tom Tucker bunny has an evil grin on his face.
- Stealth Pun: In the Disneyverse, Joe appears as a teapot. So he's "a cup of Joe".
- Take That!Stewie: How does it feel like to be on a major network for 30 seconds?Chris: FUCK YOU!!!
- The punchline of the Disney universe (where everyone beats the crap out of Mort) reflects rumors of Walt Disney's alleged Antisemitism.
- What Measure Is a Non-Human? and Dude, Not Funny!: In the World War III universe, Lee Harvey Oswald shot Mayor McCheese, with Jackie Kennedy eating the scattered head.Brian: That joke's not in bad taste, right?Stewie: Who cares? He's a cheeseburger.