An NYPD officer must live in the five boroughs, or Nassau, Suffolk, Westchester, Rockland, Orange or Putnam counties in NY- but not in New Jersey, as the production depicts. A Port Authority police officer can, however, live in a number of counties in New York and New Jersey that are in close proximity to the city.
At roughly 50 min into the film, a group of firefighters are searching through the smoke for their partner "Mikey". They find him partially buried in debris and carnage, yet one of the firefighters calls for dispatch telling dispatch "we're on the 39th floor." In reality, nothing happened on the 39th floor in the way of destruction other than maybe some lights went out. The lowest impact in either building was the 78th floor.
The World Trade Center Marriott did not have a high view into the Towers, as depicted. Therefore, the scene is unlikely where the woman looks out and watches the man jump, seemingly right across from her.
The "FDNY house" is full of errors, including incorrect helmets and a Mack CF type engine that was no longer in regular use by September 2001.
A Liberty Mutual commercial from about 2010 or later is heard on the TV when the old man is watching it.
The character of Jackie is viewing Lower Manhattan from an area of Jersey City between Exchange Place and Paulus Hook in her last scene. Hoboken, which is a few miles north of that perspective, faces the Soho area just north of the Holland Tunnel.