You cannot call or enforce a penalty after the fact by using instant replay.
JM, watch this.....
Game ends around the :50 mark.
No flag...game over... no effort by the refs to claim there was a penalty.
Now... go to the 1:47 mark almost a minute after the game ends and you see the head referee run over to take a call from the replay official, who tells him that Tenn had too many men on the field.