In terms of realism the film United 93 is high above everything I have seen before as so-called aviation films. Perhaps with the exclusion of the film about the collision over Croatie in the seventies or eighties, which also had a very high degree of realism in the description of ATC.
For those interested in the full story of the Civil-Mil (mis)communications I make reference to the NORAD tapes published by the assistant producer of the film United 93 on
www.vanityfair.com
Vanity Fair journalist/assistant producer Michael Bronner acquired the tapes after the making of the film with a note from the Pentagon that "the signing of the Declaration of Independance took less coordination". From the tapes one can read how the staff on duty on 11th September tried to get to grips with the situation, but it were the high ranking generals and civils before the official Senate enquiries who cocked everything up with false declarations which in turn have so much contributed to the conspiracy theories. The lack of Coms is to a high degree explainable in the never-seen-before panic situation, but the cover up is the really shameful part of the story.