When Captain Holt is explaining evidence about the Yo-yo strangler, the monthly crime statistics whiteboard lists 'Rape' twice. Once with 6 cases, and once with 61 cases.
Captain Holt wears his Commendation breast bar above his World Trade Center Breast Bar. When the WTC bar is worn, it is worn above all other medals, but below the American Flag bar.
Santiago is wearing 2 citation bars that are not issued by the NYPD. Also, NYPD regulations require that the American Flag bar be worn as the highest citation bar - something Santiago would have known.
Keri Brennan (played by Briga Heelan) is shown looking directly at the camera while she describes the process of being sexually harassed in an interrogation room with Jake and Amy.
A flashback of Capt. Holt and the Disco Strangler in 1981 is shown. Both of them say disco will never die and talk/behave as though it's still very popular. However it was already dead. Disco was declared dead on July 12 1979.