1. Jatta (#50) has a pretty good hold on the passrusher coming up the middle (best seen in a different angle than this one)
2. A different Utah pass rusher comes and runs the RB over....which is allowed, except that he does so with hands to the face, which is not allowed (also more visible in the angle from behind the LOS)
3. Phillips extends the arm and pushes Vaughn off, just before Vaughn grabs Phillips' shoulder
4. Zemaiah Vaughn (the Utah cornerback) gets the yank on Jojo Phillips early
5. Vaughn then wraps his arm around Phillips' torso 

Given all that, the MOST correct call would have been offsetting penalties, replay 4th down. But if we slow every play down and look carefully, I'd wager there's multiple offsetting penalties on just about every play. Calling every penalty correctly would frankly ruin the flow and enjoyment of the game.

And the first two here (the offensive hold and the passrusher hands to the face) are common enough at the LOS to get lost. They're still penalties by rule, but not egregious enough to be called/noticed there. 

Even the third and fourth foul probably doesn't get called there. It's in the first five yards, they're mixed in with some hand fighting and (fair or not, though I lean towards not) game situation has an impact on how refs call things.  And note the ref doesn't go for his flag there.

But the fifth one (Vaughn's arm around JoJo's torso) is big enough and blatant enough that it (should) get called every time. And (my opinion, and based off when the ref went for his flag) that's the part that got Utah penalized.

Interestingly, it was probably also the least impactful of the five. By THAT point the Utah defenders already had hands on Retzlaff and he wasn't going anywhere. Without that second part by Vaughn, Phillips almost certainly beats him. And it almost certainly doesn't matter because Retzlaff still goes down and the game is over. And then we're the ones sitting and complaining about the missed defensive hold (or passrusher hands to the face) and the officiating.

But the bottom line is that last action (wrapping the arm) was too egregious to be ignored, even if less impactful than the initial foul.

Utah can't (shouldn't) complain - that last part was egregious and blatant enough to leave the refs no other choice. And they still had the opportunity to hold on defense. A no-call there would have won them the game, but the call didn't lose it for them. And there were worse calls earlier - both ways (looking at the phantom facemask in the second quarter on BYU and a terrible offensive hold on Utah in the fourth that turned 4th and 1 into 4th and 10 and a punt).

That said, we have to realize we also got lucky to some extent. Not to say we didn't deserve it, but in a game that close there's going to be a lot of coin flip moments. And some went for us and some went against us, but it's clear that just one or two being slightly different (Vaughn not holding longer, the Retzlaff fumble not bouncing straight back to him), we'd no longer be undefeated.  Absolutely take the win, it's in the books, but do so breathing a massive sigh of relief