Disney Theme Parks/Trivia

Steve Martin worked at the Main Street Magic Shop at Disneyland in the 1960s, learning comedy (and borrowing a few acts from) the Golden Horseshoe Revue show.
As far as celebrities hosting Disney attractions go, Martin Short is the only one to have hosted something in both halfs of Epcot. The Making of Me, a short film in the former Wonders of Life pavilion in Future World where he gives the audience The Talk, and the current version of the Circlevision film O Canada, which pretty much has No Fourth Wall.
Henry Kissinger once took a break from his day job and sold popcorn on Main Street USA. Nobody recognized him.
In the Haunted Mansion in Disneyland, when you enter the Portrait Room, the floor lowers as to have you go through a hallway under the train tracks and into a building outside the berm, saving space. In Disney World, on the other hand, the ceiling rises (there's more room in Disney World, so the room doesn't have to move, but they wanted to keep the gags).
Early concepts for Disneyland called for Adventureland to be where Space Mountain is now (directly east of Main Street - it was built directly west instead). Some prototype maps even show parts of it existing on both sides of MSUSA.
The Epcot theme park at Walt Disney World was originally planned as a fully-functioning city rather than a theme park, and was a major part of Walt Disney's personal plans for "The Florida Project." After Walt died, the idea fell by the wayside for over a decade. When the plans were revisited, the prospect of building Epcot as a functional city exactly as Walt envisioned it was simply too impossible, so it was re-tooled into a theme park. The basic idea of Disney forming their own city was not forgotten however, and the idea was later realized when Disney created the town of Celebration, FL.
The skeletons inside Disneyland's Pirates of the Caribbean attraction when it first opened were real human remains. Walt Disney was dissatisfied with artificial prop-skeletons available at the time, so he acquired actual skeletons for the ride prior to his death. All the real skeletons have long since been laid to rest - the skeletons in the ride now are artificial.
When the original "it's a small world" was built in Disneyland Anaheim, it took all the gold leaf currently available in the United States to embellish the outer facade. Although much, much more expensive at the outset than gold paint would have been, it has already paid for itself by never needing to be replaced or retouched.
Main Street Electrical Parade has temporarily returned to Magic Kingdom twice since originally being replaced by Spectromagic, most recently in 2010 where they brought it back for the summer until popular demand saw them changed it to an open-ended run. That's what they told everyone at least. The not so well kept secret was that Spectro was in desperate need of refurbishment, and since they needed to get MSEP out of California Adventure because of concerns over crowd control before World of Color opened, they figured bringing it back to Florida was the best way to handle both situations. As of April 2012, the "open ended run" is now going on almost 2 years. However, the refurbished Spectro floats have been spotted backstage at MK signalling its return is imminent, athough no one knows exactly when.
The front of Disneyland's Sleeping Beauty Castle was originally intended to be the back. Designers weren't entirely satisfied with the original front and decided to turn it around and Walt preferred the result.
The Animal Kingdom was originally planned to have a mythology-themed area called Beastly Kingdom where Camp Minnie-Mickey is now, but it was ultimately scrapped.