King Koopa goes back in time to stop Mario and Luigi's past selves from causing the plumbing accident that brought them to the Mushroom Kingdom in the first place.
This episode provides examples of the following tropes:
- Bearded Baby: The infant versions of Mario and Luigi are shown to have mustaches, much like their adult counterparts.note
- Cargo Concealment Caper: Mario, Luigi and Toad sneak aboard King Koopa's Doomship by hiding in one of the crates that Koopa's henchmen load onto the ship.
- Fountain of Youth: Kooky von Koopa's time device goes askew, causing him, King Koopa, and the Mario Bros. to revert to babies.
- Make Wrong What Once Went Right: Koopa goes back to Brooklyn before the Mario Bros. ever set foot in the Mushroom Kingdom, to attempt to stop them from traveling there.
