I started to roll my eyes when I saw your comment because I thought, "the NYT made a fun web interactive with no-stakes and someone is pointlessly wondering if the answers are in the source code"...so now I realize what a reflection this is on how lame and limited my own thinking is :).

This was a great link...I've been casually brainstorming heuristics for detecting possible Photoshopping and John writes about exactly that. I'm going to walk through his algorithm using Python and PIL.