At the end of the movie Paxton kills the old guy in the bathroom, but he never saw the old dude at the place he was getting toutured, and never saw hes "elite hunting" tatoo. He was just some dude he saw on the train the other day.

This is not correct, when Pax was taken to the "Art Exhibit" by the brunette chick, she walks him down a hallway and he sees the old man stitching up his friend Josh.