I do wonder how basically skeletons were able to punch their way through stone tombs. I think the whole crypt thing was unnecessary. I didn't see anyone of note die to them. Much better if they started pounding and howling/snarling, which scared the people down there into making a foolish decision to run out into the keep's yard or unbar the door. Maybe then there would have been some tension and drama as some survivors had to kill others hiding to protect the many.