When it is active there are a bunch of military dudes and dudets messing around with anything from a rifle to a cannon and more, with a range commander is overseeing the whole operation. This range commander has good binoculars and a keen eyesight. If any aircraft (read folk who fail to read NOTAMS) fly overhead, his job is to order a cease fire and to identify the aircraft.
if you fly over when it is active expect an interview. If you fly over when it is not active, no one is watching and no one cares.