Coach Jim Schwartz was shown on the sidelines after Justin Forsett's stunning 81-yard touchdown saying, "That's on me." Forsett appeared to be down after a short gain on a second-and-10 play. Replays, in fact, showed he was down but the whistle never blew and Forsett rolled over and kept running. All scoring plays are automatically reviewed, but in his haste, Schwartz threw the challenge flag onto the field. By doing so, he incurred a 15-yard unsportsmanlike conduct penalty and that penalty negated the review. Source: Detroit News
I'm pretty sure I've seen several other instances when the coaches have attempted to challenge when they were not allowed to and the refs just picked up the flag.
A bigger question to me is how did the refs not see that he was down? His elbow and knee were both down. No ref saw that?
Did this game have the replacement refs in disguise? The refs missed the fact that Forsett was down how?