Thanks so much guys. I'll definitely be calling them as soon as their office reopens after the holidays. (And the class that I miswrote the grade for was in a semi-relevant field, but no, not really a big deal.)
So, another problem. I got anxious and started rechecking all my applications and then realized that, on three of them, I put down the GPA from my alma mater under "overall undergraduate GPA" when they probably wanted the combined alma mater + institution I transferred from + study abroad. Now, it's pretty obvious what my mistake was, and that I wasn't just making up some random GPA. Should I call and point this out or are they unlikely to notice (or, if they do, unlikely to care)?