The use of "Ziggy Stardust" for the scene where Andrew puts on his dad's costume and really starts giving in to his Dark Side; the lyrics basically sum up the entire story - three childhood friends who set out doing something they love, but the greatest of them (who's a Decoy Protagonist) is destroyed by going too far and it's up to his friend to put a stop to it.
Ziggy really sang, screwed up eyes and screwed down hairdo
He could lick 'em by smiling
He took it all too far
But boy, could he play guitar
Making love with his ego
Ziggy sucked up into his mind
Like a leper messiah
When the kids had killed the man, I had to break up the band.