It irritates me when the MPAA rating shows "R" but it is a made for TV movie. No way this is rated "R".
Violence: Some owie's on a couple dead bodies
You can even tell the commercial breaks.
All that aside, it wasn't a bad movie. Big, bad corporation dumping stuff in the local water supply, the way all of them do ;), makes for a flock of bats that love to eat people.