Here's the full statement from league VP of officiating Dean Blandino, who we've heard an awful lot from this season:
With 2:00 remaining in the fourth quarter of Sunday night's game between the New York Giants and Washington Redskins, Washington faced a second-and-5 from its own 41-yard line with no timeouts remaining. Quarterback Robert Griffin III completed a pass to wide receiver Pierre Garcon for four yards. The ball was correctly spotted shy of the Washington 46, bringing up third down.
Referee Jeff Triplette signaled third down but the head linesman–with Washington in a "hurry-up" situation–incorrectly motioned for the chain crew to advance the chains, which caused the down boxes to read first down.
Following a Washington incomplete pass, the chains were moved back and the down boxes correctly reset to fourth down.
In this situation where there is obvious confusion as to the status of the down, play should have been stopped prior to third down and the correct down communicated to both clubs. This should have occurred regardless of the fact that Washington had no timeouts and it was inside two minutes.
Only the referee can rule and signal a first down. The official nearest to the down markers and chain crew, the head linesman, must wait for the first down signal from the referee before moving the chains.
Instant Replay did not become involved in this situation because the replay official determined that the ball on Garcon's catch was correctly spotted short of the line to gain for a first down.
Pretty much what we identified this morning. An overzealous head linesman, and a referee who didn't stop play when he should have.
The only discipline will come in the league's regular grading sessions, which we'd really love to believe provide some sort of accountability beyond deciding who gets to work the playoffs.