The mane six and spike examine a pad that Princess Celestia sent them, and when Pinkie touches it, the seven of them are sent to different worlds.

A Disney Infinity crossover. And here's whose going to which world.
Twilgiht Sparkle: Monster's University
Rarity: Wreck-it Ralph
Rainbow Dash: Cars
Applejack: the Lone Ranger
Pinkie Pie: Toy Story
Fluttershy: Incredibles
Spike: Pirates of the Caribbean