On the issue of Savea's knock-on in the leadup to Fidow's try, had to do some digging but think I found what I was looking for in
2.2.2 of this document which, I believe, is the current TMO protocol.
It comes directly from WR (World Rugby)'s site (6.16).
"
2 Potential infringement by the team touching the ball down in opposition in-goal
2.2 The potential infringement must have occurred between the last restart of play (set-piece, penalty/free-kick, kick-off or restart) and the touch down but not further back in play than two previous rucks and/or mauls"
Seems pretty clear to me that the officials should not have been allowed to look at anything prior to the penalty against White? In saying that, there were some obnoxious TMO interventions in SRAo winding back up to two or three minutes of game play, so who knows wtf the rules are.