We'll have plenty more articles on the rest of the game, but the biggest controversy surrounding Northwestern's loss to Michigan is whether the Wolverines should have been able to snap the game-tying field goal attempt to end regulation. They got it off in time, but according to Pat Fitzgerald, NU should have had time to substitute personnel, since Michigan did:
https://twitter.com/insidenu/status/401873146870902784
However, the Chicago Sun-Times' Seth Gruen got a different answer from the official:
https://twitter.com/insidenu/status/401880910116552704
It's a little murky, but it appears he is correct:
Late in the first half Team A is out of timeouts. A pass play on third down ends inbounds at the B-25 short of the line to gain with the game clock showing 0:30. Facing fourth down and three, Team A gives no indication as to its next play until the game clock reads 0:10. They then rush their field goal unit onto the field, and Team B then hurries to respond. RULING: The umpire moves to the ball to prevent the snap until Team B has had a reasonable opportunity to get its field-goal defense unit onto the field. The umpire will step away when he judges that the defense has had enough time. If the game clock reads 0:00 before the ball is snapped after the umpire steps away, the half is over.
Did NU have a "reasonable opportunity" to get on the field? That's questionable, but the official is allowed to use his discretion, it appears.
Another contentious point is whether Michigan was set or had a false start. It's inconclusive watching the video (maybe the right guard moved), but watch for yourself: