Mark is complaining about the air conditioning in his office and blames it on being an "old hospital". But in Season 4, episode 26, the hospital is destroyed by a mad bomber - so the hospital is relatively new.
Near end, when the boy is telling his mom he thinks 'this woman' should tell what she knows to save an innocent man from being charged with murder, it makes quick cut and shows Dr Sloan and the boy and his mouth is not moving even though you can still hear him talking to his mother.