Doug Judy jokes about San Diego, and says "everybody knows that place SUCKS!" This is a running joke, as Jake similarly disparaged San Diego previously, after Amy's boring ex, Teddy, repeatedly gushed about how much he loved visiting there.
Jake asks the negotiator, "Are you negotiating?", to which the negotiator responds, "Always." This is a reference to The Devil's Advocate (1997), where Keanu Reeves' and Al Pacino's characters have the same line of dialogue.
Doug Judy and Jake mention the boy (Iain Armitage) who plays Young Sheldon and also in Big Little Lies. There are several connections between Big Little Lies and Brooklyn 99. In one episode of Brooklyn 99, the gang go to Boyle's beach house which is also the Mackenzie house in Big Little Lies. Also, Merrin Dungey is in each series playing Terry Jeffords wife in Brooklyn 99 and and a detective in Big Little Lies. Ryan Phillippe who plays Gina's baby daddy in Brooklyn 99 was married to Reese Witherspoon who played main character Madeleine Mackenzie on Big Little Lies.