Continuity mistake: In "Graduation Day", towards the end when Abby and her mother are in the apartment talking about her leaving, Abby is holding the baby and when the camera is facing her the baby is up on her shoulder. But when the camera is to her back facing her mother the baby is down. It continues like that through the whole scene.
Continuity mistake: Season 11: Episode 5: An interns guide to the galaxy: Near the end, when Ray asks if he can go home, we see Sam writing her number of discharged patients on the board in a close up. The camera then cuts back to the whole group and the size and style of Sam's writing changes. Most noticeable that the circle now stretches over the line between Ray and Abby's count whereas before it was in the middle of Abby's column.