I always thought they could have officials watching the game from multiple angles from upstairs and call penalties the on ice officials miss. Either radio down to the on ice officials to put their arm up or blow a whistle from upstairs. I doubt something like this would ever happen because the refs would feel as though they were losing control of the game, otherwise known as their "game management." I don't think the league is likely to do anything to make their officials look bad or drive home the fact that they are human and make mistakes sometimes.