In the cold open after Charles says that he slept with a 68 year old woman when he was in his 20s Jake says that was someone's grandma. After Charles says that's how they met, Jake starts laughing. It was genuine laughter from Andy Samberg.
In the scene where Peralta & Santiago are on the bus you can see 'Gina' etched into the glass to their right
Dean Winters (the Vulture) is well-known for playing Mayhem in a series of commercials for Allstate Insurance. A new Allstate commercial with Winters debuted during the premiere broadcast of this episode.
When discussing Nancy Drew, Boyle mentions Murder on Ice and Recipe for Murder. Neither of these are from the original series; they are from the Nancy Drew Files series and were published in 1986 and 1989 respectively. Given Boyles' apparent age, it's unlikely he read these as a child--either this was a mistake on the part of the writers or he actually read these in his late teens/early twenties, making his comment that he wanted to grow up to be her even funnier.
Guest star Dean Winters also plays a detective in the movie Rough Night (2017) and in the TV shows Battle Creek (2015) and Law & Order: Special Victims Unit (1999).