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.
The revolving door from Storyboard II. The participants will be separated by entering through this door. We can use one of the standard industrial designs for reference.