Deliberate mistake: The nose pieces on the face masks have been removed from all of the SCBAs used in the movie. The nose pieces are essential to keep the mask from fogging up, but were removed to allow the audience to see all of the actors' faces.
During the Christmas season (December) Travolta and Phoenix discuss a transfer to an aide's position. That same night Phoenix discusses the possibility with his wife - with crickets chirping away in the background. Not in Baltimore in December.