A new intern named Thomas the Goat gets hired to work at the park for college credit -- right in the middle of an epic battle between the main characters and nearly all the enemies they made in the series so far.
* BigBad: Garrett Bobby Ferguson Jr.
* CallBack: and MythologyGag s, too!
* ChasteToons: Garrett Bobby Ferguson's son GBF Jr. It's unclear to whether the son is illegitimate, conceived before divorce, a clone, or a product of a bizarre, asexual reproduction that only this show could devise.
* InMediasRes: The episode starts with the park already destroyed and everyone other than Mordecai and Rigby brainwashed.
* TheIntern: [[SixthRanger Thomas]].
* LegionOfDoom: The bad guys that got killed over the past 3 seasons all led by GBF Jr.
* ShoutOut: [[DragonBall The junior of a previous villain opening a portal to another dimension to resurrect his father and every previous evil villain. He is stopped when the newest and youngest character helps to defeat him sucking all the villains back into the portal]].