"Mors Praematura" is Latin for "Premature Death."
Production of this episode was shut down for a day by the Mayor's office when numerous citizens called 911 to report men with automatic weapons in the area of 47th St. and 5th Ave. Reportedly, the day's shooting was ahead of schedule and the NYPD supervisors who are required to be on scene for any exterior shots involving firearms had not yet arrived, leading to the shut-down.
Finch encloses Root in a Faraday cage. A Faraday cage is a structure of conductive metallic mesh designed to carry electrical energy away from whatever is contained within the cage. Constructed in a particular way, the cage can block mobile phone signals to the interior.
It is learned that Shaw was a U.S Marine. This is known by the USMC tattoo on her forearm.
Peter Collier (Leslie Odom Jr.) is said to "have a thing for the American Revolution." He would later go on to originate the role of Founding Father Aaron Burr in the Broadway musical "Hamilton."