The bullet fired from Lester's gun at Barnaby that struck & became lodged in the tree and recovered undamaged by Barnaby was an error. A fired bullet that strikes a hard object like the tree would've been deformed.
People begin running to the golf course for no reason other than dramatic effect. The body is not visible, and there was no hollering, screaming, or sirens. There was no reason for people to just start running.