Audio problem: When auditing the recording of one of the first hijacks, the FAA reviewer rotates the tape reels back and forth in order to find just the exact words from the hijacker. As the sounds play, the reel moves barely half a turn, but the reviewer rewinds it more than one revolution, not nearly returning to where that sound would be.
Trivia: Families of the 40 passengers and crew members killed on United Flight 93 cooperated in the production, offering Greengrass detailed background about their loved ones, down to the clothes they wore, what reading materials or music they had with them and what sort of candy they might have snacked on aboard the plane.
Question: I know this has nothing to do with movie's plot, but I'm going to ask it anyway. How did the hijackers know that destroying the twin towers would affect the US economy?