Billy Bob Thornton and John Cusack attended air traffic control schooling in Toronto as part of their role research.
Billy Bob Thornton's character (Russell Bell) states in the movie that he is half Irish (his father) and half Choctaw Indian (his mother). In real life, Mr. Thornton's father is of Irish ancestry, while his mother is half Choctaw Indian and half Italian.
Billy Bob Thornton and Angelina Jolie first met on the set of this movie. They fell in love and were briefly married.
John Cusack and Billy Bob Thornton were not able to memorize the massive amounts of air traffic controller code their characters speak in the movie, so many of their lines were printed up and taped to the radar screens for them to read like cue cards. Cusack called it "doing a Marlon Brando".