(at around 12 mins) When Sonia makes a comment about her past relationship with Espo, and Castle's face lights up in excitement, Seamus Dever ad-libbed Ryan slapping his hand over Castle's mouth before he can say anything.
First appearance of Esposito's family.
Lucy and Linus are the Van Pelt siblings in Charles Schulz's "Peanuts" comic strip.
Castle is indignant that Lanie assumes he was at fault for his and Beckett's separation. He's actually in the right; Beckett left him because of what Rita told her in XX (2015) - that she had to choose between being with Castle and hunting LokSat.