At the very end of the show, when Leading Player tells the company to take out the sets, kill the lights, etc., the stage lighting deconstructs, and the nasty fluorescents over the heads of the audience come on, as well.  The fluorescents in the house are above the massive and foreboding trusswork and catwalks, and cast shadows on the walls of the theatre quite similarly to the ones you see below, on the back wall.   It all worked together beautifullly, and the audience was squirming in their seats when the lights are turned on them!
(Oh, a note:  Theo (the little boy) is usually onstage at this moment, but this was a dress rehearsal that was running long, so we sent him home!)