Reference to 'Into The Wild'

I just watched this and thought it was interesting that he used, almost verbatim, Jon Krakauer's premise from "Into The Wild", the story of Christopher McCandless journey into Alaska as his closing piece. He even went so far as to give him a young stoner persona. I don't remember seeing any acknowledgment in the credits. Which I'd find odd coming from a man deeply steeped in Literature and performance. Anyone got any info on this...?