When a guy has to choose whether he or his son gets shot, you hear a hammer being pulled back on more than one occasion. The baddie is using a Glock that does not have a hammer.
Near the end of the movie when they were talking in the kitchen you can see a left arm in a black t-shirt behind her.
Around the 36 minute mark, where they are pulling away from the father/son double homicide, the 'NYPD' detectives' vehicle has a NJ license plate.