When Beckett and Ryan talk to the arson investigator at the crime scene, and Castle hurries out of the building before it collapses, Stana Katic ad-libbed Beckett's embarrassed mutter "I'm marrying him".
When Castle asks Ryan if he and Jenny have picked a name for their baby, Castle suggests "Cosmo". Until they learn his identity, this is the alias he gives Baby Doe discovered with the victim in "The Good, the Bad & the Baby (2013)," stated as being the name he would have given Alexis if she'd been a boy.
The folders for the cases from the fire department say "NYFD" as opposed to the proper "FDNY"
Guest star Wendy Davis played a main character in Army Wives (2007). Seamus Dever guest starred in the second season as Dr. Chris "Getty" Ferlinghetti.
Guest star Wendy Davis (Lt. Delia Burton) played Lt. Colonel Joan Burton in Army Wives (2007) from 2007-2013)