Be sure to check out the updates to this post HERE.
More material was added to this post Nov 1, 2012 and Feb 20, 2014.
When discussing the influences that stimulated this or that element in the Mansion, it would be a mistake to overlook the movies. By their own testimony, the Imagineers watched spooky films as part of their research, looking for useable ideas. Whenever this topic is raised, there are two cases that are routinely trotted out to illustrate the point, but rarely does the discussion go much further. As usual, Long-Forgottenistas demand more. We shall cast a wider net, and hopefully it will catch us some strange and interesting fish.
The two well-known examples are the bulging doors in the Corridor of Doors, a gag taken from Robert Wise's 1963 horror film, The Haunting, and the human-arm sconces in the crypt, inspired by Jean Cocteau's 1946 interpretation of the Beauty and the Beast story, La Belle et la Bête. The latter film in particular was (I should say "is") a favorite of Rolly Crump.