Here’s what happened when refs threw a flag on “Connor Barwin” for being an ineligible receiver. From Pro Football Talk:

So what happened? Justin Rogers of the Detroit News reports that the official who threw the flag forgot which team was on offense and threw it on Lions defensive end Devin Taylor, who wears No. 98. Morelli heard his fellow official say there was an ineligible man downfield on No. 98, and called it on the offense, and it was only after a conference that the officials figured out their mistake and waved off the flag — without telling the crowd.

“Yes, the ineligible receiver that they called downfield was Devin Taylor,” Lions coach Jim Caldwell said after the game. “Then he realized that he called it on Devin and said that’s why they picked the flag up.”

They forgot which team was on offense. That usually stops happening after Pop Warner football when little Ken Bone takes one to the house… against his own team. Usually.