While the E.R. staff is watching coverage of the accident, there is no snow on the road or any of the surrounding area, despite a massive snowstorm going on.
While working on the patient with the amputated leg, the blood spurts on Nurse Lydia's face, for the remainder of the scene, the blood is gone.
Near the beginning, Carol is shown entering the ER twice when the character only entered once. The first time is immediately after she is hit by the snowballs, and then the second time is a minute later as the credits are listing CCH Pounder.
Right before announcing "Stat Dr. Carter", you can see an director's chair on the left with someone sitting in it.