Weirdmageddon

"Weirdmageddon" is the three-episode/four-part series finale to Gravity Falls. The first two episodes were broadcast individually on October 26th and November 23rd of 2015, respectively. The last episode, which makes up the last two individual parts of the story arc, premiered as a one-hour special on February 15, 2016, and will begin airing as two individual half-hour episodes in March. A two-hour "movie" version of the episodes put together premiered on Disney XD on February 29th.

Part 1: "Weirdmageddon Part 1"
Picking up right after the events of "Dipper and Mabel vs. the Future", the apocalypse begins, and Dipper and Wendy head out east in attempts of rescuing Mabel.

Part 2: "Escape from Reality"
Dipper, Wendy, and Soos find themselves in a fake reality fueled by Mabel's imagination, and need to convince her to leave the bubble before they get tricked in by its temptation.

Part 3: "Take Back the Falls"
While Ford discovers Bill's true motives for his plans, Dipper, Mabel, Stan, and the rest of the resistance head out to stop Bill once and for all.

Part 4: "Somewhere in the Woods"
When Bill traps the resistance members and threatens to kill Dipper and Mabel, Stan and Ford are forced to come up with a new plan to defeat him, but they will have to make the ultimate sacrifice.

Trivia

 * Shortly after arriving in Mabeland, Soos comments, "What is this new world? Shining, shimmering, splendid." The last three words are lyrics from the song "A Whole New World".
 * In the two-hour movie version, besides the obvious exclusion of the opening sequence in the later parts as well as the credits scenes for parts 1 & 2, the shot where Multi-Bear comes out of the bathroom at the end of part 2 was cut to provide a better transition into the opening of part 3. Also, voice credits for characters who only appeared in the first two parts were added into the closing credits sequence, and immediately following the live-action shot of the Bill statue, all four parts' ending page sections are shown one right after the other.