MNF: Did I hear that correctly?

[OverAndBack]

Illegal formation penalty on Pittsburgh just now in the Monday Night game - Al Michaels says that it was so loud, the players couldn't hear the whistle that the play was dead, so they continued.

Am I wrong, or is illegal formation a foul at the snap? So you wouldn't shut the play down? Or is it different in the NFL?

The play-by-play says:

(14:47) B.Roethlisberger pass incomplete to A.Randle El (D.Edwards).
PENALTY on PIT-H.Ward, Illegal Formation, 5 yards, enforced at PIT 16 - No Play.

Is it no play because they took the penalty, or because there really was no play because it was shut down? And if it was shut down, you wouldn't note the incomplete pass?

I'm thinking Michaels got it wrong, but I want to check to make sure.