Carisi states he has a new niece, meaning that his sister Bella gave birth after she was shown to be pregnant in the episode Parole Violations (2015).
Chris Elliott (Pete Matthews) previously played the role of Anton Thibodeaux in episode 10.4, Lunacy (2008).
Dodds (Andy Karl) says "They could be Irish twins". The term "Irish twins" refers to one mother having two children, who were born 12 months or less apart. It originated in the 1800s as a way to poke fun at Irish Catholic immigrant families, who did not have access to birth control. Irish Catholic immigrant communities would often have many siblings, who were very close in age. Since they were relatively new to the United States, and lived in cramped living conditions with little resources, other people would speak poorly of them.
Pastor Gregory Eldon (Ryan Devlin) says "You live in Gomorrah" to Hobbs and Fin. This appears in the Old Testement (Genesis 19:24); Gomorrah was one of two ancient cities near the Dead Sea, the other being Sodom, that were destroyed by God as a punishment for the wickedness of their inhabitants. It can also refer to any place notorious for vice and depravity.