Dueling Movies: Was released around the same time as Flight Plan, which also revolves around a woman on an airplane terrified for the safety of a family member. This film though was a little better received.
When Lisa bumps into a woman and has coffee spilled on her clothes, Rachel McAdams's reaction is genuine. She did not expect the coffee to be so cold, and it had spilled on her more than she had expected.
Though not featured in the film, Cillian Murphy had missed the spot to throw Rachel McAdams while filming the lavatory scene, knocking her unconscious for half an hour. When they had to film the scene again, Murphy was afraid to. This scene can be found in the bloopers. The scene featured in the film briefly shows that Murphy has his hand behind McAdams's head to protect it.
Executive Meddling: The terrorists were meant to be American, but the good people at FOX did not like the idea of this, hence why they switch from speaking English at the start to Russian later in the film.
Fake American: Cillian Murphy is Irish and Wes Craven was initially wary about casting him as Rippner since Rippner was explicitly written as American. When Murphy walked into the audition, he actually fooled the casting agent with his accent.
Also, there's Canadian Rachel McAdams and Australian Brian Cox.