Ok, a brief history of The Ladder: *ahem* A long time ago in a theme park far, far away...
A glorious attraction was under construction. An attraction that, when completed, would constitute the most powerful weapon in the DISNEY REBELLION'S ongoing stuggle against UNIVERSAL, sworn enemy of the GALACTIC ALLIANCE. A lone soul was instrumental in the construction of this weapon: the young Jedi, LUKE SKYLADDER. This plucky young rebel held the key to defeating the EVIL EMPEROR MUMMY and paving the way for TRUTH and JUSTICE in the galaxy...
:lookaroun
Translation: during a photo update of the construction of Mission: Space, a ladder kept showing up. A joke started along the lines of "The attraction will now be 'Mission: Ladder'" and degenerated from there.