The episode spans across 6 months, and Amy is said to be pregnant at the beginning of the episode. Yet, at the end of the episode, Amy is not visibly pregnant.
While Amy and Charles are in the break room discussing Jake's therapy, at one point the slats of the blinds over the windows are slightly parted (where Amy had been watching the bullpen). The scene cuts to Charles and then back to Amy and suddenly the blinds are closed flush.
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.
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.
Despite wearing his captain's uniform in the previous episode, Holt is back to wearing his patrolman's uniform during this episode because (not counting the "in media res" cold open) it begins with flashbacks to the previous October and February, before he was reinstated as Captain.
It would have been impossible for anyone to have changed into the bunny costumes without first being uncuffed from their teammate.
When Holt orders the others to bow down, Charles drops down to one knee, but does not lower his head, which is what defines a bow.