Twelve men on the field might be the only one you can challenge. I seem to recall that being a named challengable item.
BTW, at least last year, IF a legitimate challenge was initiated, penalties could be assessed or reviewed during the process of reviewing the play. I've yet to see it happen, and who knows, they might have removed that aspect of review.
I can't be 100% certain... but I faintly remember a time when a play was being reviewed last year and during the review they could clearly see a facemask that had not been called... and I thought they assessed that penalty.
Again, I could be wrong on that memory... but I know I remember the Belichick one clearly as the announcers praised him for knowing he could make that challenge.
At least in this case we aren't talking about a goof/miss that changed the game. All the Titans turnovers, especially in scoring territory, are what cost them and they said as much post-game.
Carolina really let me down. I was rooting for San Diego but I knew Pitt was good and perfectly capable of a beatdown... but I expected at least some fight from Carolina against Arizona.
At least big kudos and congrats to Arizona and now they get to host the NFC championship game!