In Town Square, there's a secret apartment above the Fire Department. Admittedly Walt and his family visited it as an actual residence when they didn't want to be noticed.
Splash Mountain was named "Flash Mountain" due to the case in the late 90s', when visitors started baring their breasts for the camera located before the final drop.
Some people claim that you can keep whatever you find there, as long as you fill out a form and it isn't claimed next two months. Nevertheless, Disneyland, says this is just a tale.
The "Tree of Life" in Animal Kingdom was constructed around an old oil rig so it could withstand the hurricanes that usually hit Florida.
In Disney World there is for a wedding ring embedded in the concrete in line at The Haunted Mansion. It's commonly believed that they belong to the hanging bride that can be seen in the stretching room and attic scenes on the ride.