In the scene where Mark Wahlberg's character is meeting with the government officials after scouting possible shooting locations, Danny Glover's character tells Wahlberg that they could use him as a spotter on the day of the President's speech. Wahlberg smiles in agreement and walks off, shown in slow motion. During this interaction, an American flag can be seen hanging vertically in the background on the wall. It is displayed with the blue starred section hanging on the right (that is, the top edge of the flag is to the right). According to the Flag Rules and Regulations (http://www.ushistory.org/betsy/flagetiq.html), when the flag is hung on a wall, it should always be flat with the blue area in the upper-left corner. That would require the flag to be hung opposite from the orientation shown in the film, with the top edge of the flag to the left.