The Ravens will certainly pick up at least a few penalties in this game. Sure, they had no penalties last week but they were at home. The road team is usually good for at least a couple of false starts and if their defense comes out as aggressive as most are predicting, that might lead to a few other calls.
If the Pats defense plays with the same fire that had last week, it will be a long day for Flacco. And the Pats pass rush is actually decent. I believe the Ravens had 48 sacks on the season and the Pats had 40. Of course they lost a bunch of those when Carter went down but they are still getting after the QB better than in the past few seasons.
The Broncos run game was excellent all season and the Pats did a nice job of limiting that last week, at least compared to how they fared in the first meeting. This week they don't have to worry about the option, a run-first QB or any of that so they can focus on Rice.
I think the biggest key, aside from keeping Brady upright, is getting out to a fast start and a lead early. That will put the pressure on the Ravens offense and Flacco. The no-huddle, hurry-up offense for the Pats will likely also be key.