The song playing inside the elevator as Elizabeth Corday goes down to the ER for the first time since her husband, Mark Green, died, is Billy Joel's "Piano Man." That is also the same song that Mark and Elizabeth sang together when they did karaoke at a restaurant the night Carter and his med student, Lucy Knight, were stabbed by a schizophrenic patient.
In the opening scene where Carter and Abby are in the bathroom listening to the radio, the radio announcer says it's "8:30", then Abby says "There's an 8 o'clock meeting near here" after Carter informs her her shift doesn't start for two hours.
Elizabeth finds a photo in the lounge of Carol, Susan, Chuny, Haleh, Lydia, all standing around Mark.