Carol's water breaks on the El, but when she loses consciousness on the stairs after getting off and Luka picks her up, her pants are clean and dry.
When Greene asks Carol if she wants to talk just before Abby comes in, Carol's hands on her stomach change position in between shots.
In the last scene, the cry of the baby in the bassinet is not that of a newborn.
When they moved Carol into the O.R. and she made Mark promise her they will save the baby, the sheet over her belly slips and the fake belly becomes visible for a split second.
At 18m 37s, a man wearing jeans and sunglasses can be seen kneeling down behind Dr. Kovac when he is assessing the older patient in the trauma room.