After Anti-Pops and his bounty hunters arrive in an Uber-like taxi following the destruction of most of the former's ship, Pops tries to convince him not to fight because they are brothers.
To ensure his friends' survival, Pops makes a deal with Anti-Pops: whoever lands the first blow in battle gets to decide the fate of the universe.
Meanwhile, the park crew, HD DVD, Blu-ray, the Baby Ducks, Toothpick Sally, Recap Robot, Chance Sureshot (whose prior "death" in "Space Escape" is revealed to be that of a clone), the Guardians of Eternal Youth, Gary, Carter and Briggs, Death, Party Horse 42699, and the Guardian of Lolliland (who is supposed to remain neutral) fight against Anti-Pops's minions, Streaming, and the Stream Box Bots (who merge with their master to power him up) and manage to defeat them.
Anti-Pops proceeds to erase the rest of Pops' allies and friends except Mordecai and Rigby, and kick his brother into a portal.
As the two brothers' punches collide (with Mordecai and Rigby between their knuckles), it obliterates the entire universe and resets time.
However, Mordecai does not remember, so Rigby shows him the stash of buried Blu-rays (from the previous episode "Cheer Up Pops"), which triggers his memories of the series' events after touching it.
After three years in space, the park workers fly back to Earth, where they reunite with their friends and families and are welcomed as heroes.
Muscle Man and Starla move into a better trailer in the park and have many children, who adopt many of his mannerisms (like taking off their shirts and yelling).
At their 25th anniversary reunion, the park crew raises a statue of the now-deceased Mr. Maellard next to the one of Pops and take a picture in front of it with their families.
As the reunion party commences, Mordecai and Rigby (now 54-years-old) reminisce on Pops' sacrifice and how none of them would have been able to lead such beautiful lives without him.
It is then revealed that Pops is watching his friends in what seems to be an afterlife (presumably Heaven) on a VHS tape labeled "Regular Show".
The writers and storyboard artists were Benton Connor, Madeline Queripel, Casey Crowe, Owen Dennis, Minty Lewis, Ryan Pequin, Sam Spina, Gideon Chase, Alex Cline, and newcomer Sean Glaze.