Big Thunder Mountain Railroad, 2003
On September 5, 2003, a single train car filled packed full of unsuspecting riders broke free from a locomotive in a tunnel on the Big Thunder Mountain Railroad rollercoaster in Disneyland. After it derailed, a number of people were trapped in the tunnel.
Source: Twitter
Tragically, a 22-year-old man died, and 10 other riders, with ages ranging from 9 to 47, were injured. The most serious injury consisted of broken ribs, chest injuries, and facial cuts. It took over an hour to remove them from the car; eight riders were rushed straight to the hospital, while two had to be treated at the scene.