I think he was, there's a picture in this article to show it:
http://www.sbnation.com/nfl/2015/12/1/9825602/ravens-browns-ending-block-kick-six-refs-blown-call
Also, that guy was CLEARLY in the neutral zone but bad teams just get bad breaks. To not review that final play was lousy even if not overturned.
You may be right, but that 'line of scrimmage' line in the photo isn't official, it's put there by TV. I believe the article points that out. I don't even know if it would appear in what the refs would see in a review, probably not because it's not part of the field of play.
It's always a shame when a game gets down to one play, and a phantom 'missed call.' The truth is that in football, should they choose to do so, refs would have reasons to throw multiple flags on every single play.