Actually I'm watching the Tivo of it now and I forgot about THE key play (one PacerTom mentioned).
3rd down, up 21-3 the Pats complete a pass to the 20 to Watson for the first down. About to go up at least 24-3 and maybe worse....
PASS INTERFERENCE ON TROY BROWN. Back to the 38.
Then a run that gets them maybe into long FG range...illegal shift on Watson. Back to the 43.
Brady sacked at the 50. No points at all. Colts stay within 18.
Even if Watson dropped that first pass the Pats still had a good FG shot without the PT on Brown. Those 2 penalties, the first 2 on them all night, saved the Colts chances by keeping it a bit closer.
BTW, I sat on the other side so watching the TV coverage is kinda disorienting. I remember everything from the other angle.