Kelly Giddish's final episode as a series regular.
This episode was originally titled "Partridge In A Trauma Pear Tree" until a fan suggested to showrunner David Graziano on Instagram the name "And A Trauma In A Pear Tree", saying that it would be a fun singalong name. Graziano stated that he liked the name the fan had suggested much better than the original name and agreed with the script coordinator to have it changed.
The song that plays during Carisi and Rollins wedding reception is "As Long as It's Real" by Raphael Lake. The song is also played during the episodes Intent (2017) (S19E08) and Down Low in Hell's Kitchen (2019) (S21E03).
A police officer has limited authority if they are out of their jurisdiction, for example Olivia being a NYPD detective her jurisdiction is limited to the New York city limits. A law enforcement officer can pursue a suspect from an active crime across jurisdictional boundaries like city and county lines, but they are expected to notify the local law enforcement in the jurisdiction that they are operating there. Same goes if they have an arrest warrant for someone outside their jurisdiction, if city police need to arrest someone outside the city limits they notify the county sheriff's department and the sheriff escorts them to where they need to make an arrest. A police officer can also arrest someone out of their jurisdiction if they witness a crime, the same process as a citizen's arrest, but when they do this all they can do is detain the suspect at the location where they arrest them until the local law enforcement arrive on the scene to take custody.