When Beckett and Castle are talking in bed, Beckett's shirt is alternately on and off her left shoulder.
When in bed Castle says the saxophone was invented by Anton Sax instead of Adolphe Sax.
At the beginning of the episode, when the victim is dropped off in front of the emergency room, one nurse tells another to go for help "now". The universal medical shorthand for doing something immediately, especially in such a medical emergency, is "stat".