Continuity mistake: We see a nurse writing down "Yang, C" on the assignments board; note the handwriting. Later, when Burke notices that Christina's name is on the board, the handwriting of "Yang, C" is completely different and other minor writing differences are noticeable too.
Continuity mistake: When Derek sits in the rocking chair in the room with the premature baby and then Addison starts listing their relationship options, the blanket hanging over the back of the rocking chair constantly changes position, evident by the green stripes on it.
Continuity mistake: As Meredith tries to get in to see Christina, but Bailey walks over to stop her, Meredith is putting on a white surgical mask. In the frontal shot she ties the white straps of the mask into bows. But in the next shot from behind the straps hang loose and aren't in bows.