Apart from a couple of second unit shots of Washington DC and one scene shot in a park, all filming took place on sound stages in Montreal, Canada, with extensive blue screen techniques used to create the "world" around each set where required.
Though it may be considered an error by some the patch on the Task Force 160's helicopter pilot's shoulder showing the symbol of the 82nd Airborne Division is correct. By military tradition any soldier is allowed to wear the insignia of a unit s/he had served in combat on the right shoulder of their uniform...their current assignment insignia would be on the left.
Initially rated PG in the Canadian province of Ontario, but the Ontario Film Review Board decided to revise the rating upward to 14A on August 21st, 2013, even though the movie had been in release for almost two months by that point.
When the people at the Pentagon are discussing the black ops that Stenz had been on in Pakistan, the last black and white picture that appears on the screen is cover art from the Call of Duty: Modern Warfare" series of video games.
Before the Delta Force Black Hawks are flying in Washington D.C, the Commanding Officer is referred to as Lieutenant Colonel, then later referred to as Colonel. Although some think this is incorrect, a Lieutenant Colonel or Colonel in the Army can be simply referred to as "Colonel".
They had to build 45 sets in two and a half months because of the rushed production schedule, including the bulk of the White House, the Pentagon, the Capitol, tanks, aircraft, Marine One, Black Hawks, etc.