IF,the arrow did not pierce hide with broadhead exiting and eventually falling out broadhead side,
He is in trouble. He could drop on it or roll,try to bite it ,but if its inside under hide the arrow should act like a knife handle. If blades entered razor sharp it would help but treating him as a gut shot seems best recourse. In morning tracking would show plenty of blood if a ham pierced,foul stuff if guts. Sure would expect to find him after some no fluid tracking for a short distance but sounds like a dead deer. Good luck and remember a pic!.