With the exception of shooting scenes on the Lincoln Memorial and the Ronald Reagan Building, most of the scenes taking place in Washington D.C were shot on sound stages including the main chamber of congress which was 30ft high and 450ft long. It was so good that representatives of The West Wing (1999) TV show even expressed interest in buying it.
To build a so-called "stealth tank" for one of the sequences in the movie, the production designers took a used truck chassis, shortened it and placed a Freightliner diesel truck engine onto it. "Stealth" panels were then placed on top of it to give the tank its unique look. Tracks were taken from another piece of heavy equipment and fitted onto the "tank". Even a double barrel turret was constructed that could counter rotate.
Two scripts were written for consideration. One by Rich Wilkes involves pirates in Southeast Asia and the other, by Simon Kinberg, involves a plot set in Washington D.C. The Simon Kinberg script was selected. Open casting calls in the Baltimore-Washington D.C. area were made on 19 August 2004 and 26 August 2004. Shooting would start on 14 September 2004 and go through 1 October 2004. Rob Cohen had earlier suggested that that both scripts may be made, with the one not used for XXX2 becoming XXX3.
The rifles that Deckert's men use during the attack on the NSA and in the Chamber of Commerce scenes are replicas of the experimental XM8 assault rifle. They are actually visually modified German G36K assault rifles, as can be seen from a visible hinge allowing their stocks to fold.
Towards the end of the film, Stone uses the phrase 'Son of a bitch stole my line' in response to the Presidents speech. Stone's response was in fact used before - by Robin Williams in Good Will Hunting (1997).