This situation made the CFO weekly video. Tough learning moment. Hope they don't get too much 'consequences.' Everybody has to be paying attention, including replay, at all times. Never be afraid to question the down number (or anything else, for that matter), if there is any question in your mind. They could have fixed it, all the way up until the ball was snapped for the first down of the next series. Unfortunately, that didn't happen.
Let us all learn this lesson.