I recently came across a number of pages claiming things like "6 Secrets Disney doesn't want you to know", or "Disney's Dirty Secrets". While there may be truth to some of what is said, in a lot of cases it really isn't likely - or a secret for that matter. Here are some of them - and facts to go along with them.
The truth behind them is that after seeing cast members from one are of Disneyland having to cross another area to get on and off stage, Walt wanted to make sure that couldn't happen. So when the Magic Kingdom was designed he wanted to make sure there were hidden passages by which cast members could reach their areas without being seen. To accomplish that, they actually build the corridors at ground level - and then filled in the land to put them underground. The Magic Kingdom was actually raised up higher than the original ground level - what you see as the first level of a building is actually the second floor! Now THAT is something fewer people know about.
Go ahead, if you really want, do a Google search. Take a close look at the pictures. No, not there...but look at the ride itself. Very few, if any, of the rides are actually Splash Mountain, but flume rides from various other parks. Fact is, this occurs in many places. "Flash Mountain" was just a catchy name. Also, Disney knew this would occur, and to maintain the family-friendly environment where all pictures are displayed (albeit briefly) to the public, a cast member was assigned to "filter" the pictures. Anything remotely obscene (even a guy showing a bare chest) would not be shown and not available for purchase.
However, many people have essentially died at WDW - notable incidents revolving around Mission: SPACE were widely publicized as well as a few cast member deaths. And people have in fact been pronounced dead on property, as early as 1984 with a small plane crash in the EPCOT Center parking lot (New York Times, Nov. 22nd, 1984)