In the spooky mansion, mice run around in response to lightning and other events. A hole in the floor blows up air, actuated through vents by a simple pneumatic pump controlled by a remote circuit. This gag provides a scary effect, consistent with the theme, and shouldn't be too hard to build.
An old gramophone fits the scene and can be used in conjunction with a puzzle. The clank can be connected to an electronic trigger. An old gramphone can be retrofitted with electronics for the purposes of this gag.
