On the play pictured above, Detroit Lions rookie Ndamukong Suh(notes) brought down Dallas Cowboys running back Marion Barber(notes) by his hair and facemask. One of those methods is legal, the other is not.
Yet when the referee in the game announced the penalty, he said it was for Suh's horse collar tackle, a violation which, while illegal, was never committed by Suh on the play. The rookie's left hand clearly pulls Barber's hair. It never goes inside the jersey. As such, there shouldn't have been any penalty for what Suh did with his left hand.
FOX announcers Daryl Johnston and Tony Siragusa agreed with this, as did FOX's officiating consultant, Mike Pereira. As they stated during the broadcast, tackling a player by his long hair is perfectly legal in the NFL. (Incidentally, it was Pereira who clarified that to officials in 2003 after Ricky Williams(notes) was twice tackled by his dreadlocks.)
So, the official was wrong and Suh was flagged for a violation he didn't commit. But here's the thing: Suh still deserved a 15-yard penalty on the play. As you can clearly see in the picture above and in the video clip below, the Lions defensive tackle grabs Barber's facemask. (The play begins 43 seconds into the video.)
The 15-yard penalty for the facemask would have been the same as the one Suh got for the non-horse-collar horse collar. Whether the ref simply gave the wrong explanation or whether he got bailed out by the fact that Suh also happened to commit an actual penalty had no relevance on the game. It might earn him a lecture during his weekly performance review, however.