U.S Military Air Traffic Controllers were used in some scenes for the movie.
The Military controllers were only used during the military scenes. The civilian air traffic scenes were done by real FAA air traffic controllers.
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.
The actors who played the terrorist hijackers and the actors who played the passengers and crew on the flight were kept in separate hotels during filming. They also worked out in separate gyms and did not eat meals together. This was so that the director could capture the separation, fear and hostility between the two groups of antagonists and protagonists.
The filmmakers donated a percentage of the opening weekend proceeds to the Flight 93 memorial near Shanksville, Pennsylvania. The actual amount donated turned out to be $1.15 million.
The ensemble cast of mainly unknown actors were each given studies of their real life United Flight 93 counterparts. Director Paul Greengrass was then able to partially improvise some of the events for the film.
The Iraqi-born (but London-based) actor Lewis Alsamari, who plays the lead hijacker in the film, was denied a visa by US immigration authorities when he applied to visit New York City to attend the premiere, despite having already been granted asylum in the United Kingdom since the 1990s. The reason given was that he had once been a conscripted member of the Iraqi army - although this was also the grounds for his refugee status after his desertion in 1993.
The United 93 flight crew is entirely portrayed by real pilots and flight attendants, some of whom actually work for United Airlines.
Voted Movie of the year by Empire magazine.
The pins on the uniform worn by Trish Gates in the film, are actual airline pins that belonged to flight attendant Sandra Bradshaw. They were donated by her husband, Phil Bradshaw, to replicate her uniform for the film. Gates was herself a flight attendant for United Airlines shortly before participating in the film.
Ranked #16 in Entertainment Weekly's "The 25 Most Controversial Movies Ever."
There are no indications that the German passenger Christian Adams really acted the way he did in the movie. The story of the only European victim trying to stop the others from attacking the terrorists is fictitious and not based on any recordings or phone calls made in the plane.