House On Haunted Hill is the only film to be made with the quaint cinematic process known as Emergo. Now, Emergo was an early prototype of a truly holographic 3D movie process that wouldn't require the audience to wear silly glasses. Emergo was a simple motion path generator consisting basically of a...skeleton...on a wire. There's a point in the film when the skeleton would be pushed out from the top of the screen along a wire above the heads of the audience. They stopped it when kids kept shooting at the skeleton with BB guns and, in some neighbourhoods, Uzis.