One of the smartest things the movie does is make fun of itself. It poinst out that it copies the “you kill my enemy, I’ll kill yours” device that’s been done before, and more than once. The script makes reference to the ’80’s version of this plotline (also done with humour) “Throw Mama From The Train”, and goes even further to pay homage to the original film that incorportaed this plotline (with no humour at all, just sinister chills), the Hitchcock classic “Strangers on a Train.” Once the movie lets you know that the movie-makers know they are copying and updating a well-worn storyline, there’s nothing for the naysayers to pick on.