There was an old Bugs Bunny cartoon where a truck carrying a load of hats lost its door somehow, and all the hats went flying around in the wind. Whenever a hat landed on someone's head, it changed that character's behavior to match the hat.
Think of what could be done with all the props and costumes lying around in Hollywood.
Another idea I had was that a prop could be infused with energy according to the movie it was used in. Since even the lowest budget/lowest selling movies usually represent hard work on the basis of somebody, or somebody's heart-felt dream, such a prop could be as likely to be for a little-noted movie (such as the glass skulls used in The Phantom) as for a blockbuster (such as the Batmobile). Of course, a prop could have been used in a porno movie, as well. Some of those beds are probably still around.
(Okay, an idea here involving a bed, a predator, and a heroine, better turn the camera off now...)
Ideas: A possessed Batmobile. A cloak of the cultist. Handcuffs of carnal delight. The glass skulls from the Phantom. The radio from Gilligan's Island. John Wayne's hat.
An idea for a new menace: The Paparazzi. Some people just don't know when to quit. Long after the Dang, when their undead bodies had crumbled into dust, the cameras of the paparazzi still stalk the streets of Hollywood, looking for news,and flashing photographs of whatever they encounter. Of course, they long ago ran out of film, but the cameras will continue to flash until the Sun goes supernova.