Mad Props: Each of the props described is found (uniquely, I hope) in a movie. Taking letters from the different answers results in an acrostic-style solution: SIMPSON AND WISCONSIN ARE NOT the culprits. The answers to the individual movie props:
Ubiquitous ducts - Brazil
A teenager’s t-shirt, purchased in an emergency for one hundred dollars - No Country for Old Men
Photographic flash bulbs used to impede the advance of a murderer - Rear Window
A row of parking meters with their heads removed - Cool Hand Luke
A deliberately shredded opera program - Citizen Kane
A trainload of rotting vegetables - East of Eden
Multiple borrowed sticks of gum, to be paid back later - The Right Stuff
A hand of four threes that mysteriously becomes a hand of four jacks - The Sting
A golf club for exorcising demons - Dogma
False teeth used to stop time - The Hudsucker Proxy
Strange Motif: This was inspired by a puzzle taken from the Kaitai Dismantlement series of puzzles (look it up if you aren't familiar, it's really fun). If you print out the puzzle, cut apart each shape along the solid lines, and rearrange the pieces such that the icons line up with one another, you will spell out the letters RLSTINE.
Travel: The cities in the pictures ("visited") are of Seattle and SF, followed by Dallas, Minneapolis, Chicago, Atlanta, Chicago, and Omaha. If you draw lines connecting these cities, showing how RL Stine has been traveling recently the legs of the trip will spell out I (Seattle to SF) and A. Hence, the answer is IA or Iowa.