In this episode Ted says that he lost his hair in high school, while in the first season he says he still had hair when he started working for Kelso.
When Cox interacts with Elliot and her rounds, he has his stethoscope on the outside of his coat, a moment later it's on the inside.
When J.D. sees Molly and screams, he fumbles backwards and collides into a doctor, Molly's hands shoot up to her face. In the next shot, she has her arms by her side.