The woman at the check-in desk at the airport tells Alex that the plane leaves at 9:25, which is the same as his birthday (25th September). When he gets on the plane he sits in seat I (which is the 9th letter of the alphabet) and the seat is in row 25.
The original plan was to have death as a much more obvious entity in the film as it was in Tod's death (with Tod seeing a shadow in the mirror and the water running back into the toilet to "cover its tracks"). After Tod's death it was decided to have the deaths simply as accidents.
As well as footage, this movie borrows in other ways from the crash of TWA Flight 800. The July 17th, 1996 flight was carrying a high school French club, it exploded suddenly and was investigated for a possible deliberate act causing the accident - first a bomb, then a surface to air missile. As with the movie, it was ultimately decided that the crash was a result of mechanical failure (explosion in the central fuel tank), although the FBI investigation is still open.
The numerous appearances of "180" in the movie refer to the film's original title of "Flight 180". New Line decided to rename the film to "Final Destination" through fear of confusion of other movies like Air Force One (1997) or Con Air (1997).
Most characters in the film are named after directors or stars from black and white horror movies: Chaney (Lon Chaney); Waggner (director George Waggner); Browning (famous "Dracula" director Tod Browning); Larry Murnau, (after F.W. Murnau, director of the "first" Dracula film Nosferatu (1922)); Schreck (Max Schreck also starred in "Nosferatu, eine Symphonie des Grauens"); Valerie Lewton (Val Lewton produced several famous horror movies); Blake Dreyer (Carl Theodor Dreyer directed Vampyr (1932)); Howard Siegel (Don Siegel' directed Dirty Harry (1971)); Billy Hitchcock, whose name pays homage to Alfred Hitchcock.
The scene where Carter elbows Billy in the car was added in because on the day of shooting that scene, Seann William Scott had a sore lip. To hide it, the make up team added blood and the end result was of Carter elbowing Billy.
Many of the props contain references to assassinated presidents or almost-presidents: Ms. Lewton's leaking coffee cup had an inscription for Mt. Abraham High, and Carter Horton's car had a license plate beginning with the letters "RFK". The plane takes off from "JFK"-Airport. JFK (John F. Kennedy) also was assassinated.
When Clear gets out of the car to find Alex on the beach, a real beach was used with some trees placed at the roadside to make it appear like she is walking through a maze to get to Alex. Once the shot closes in on Alex, a set is used to stop the water effects from the real beach getting on to the soundtrack of the scene.
The trivia items below may give away important plot points.
In the scene where everyone stares at Alex after the plane explodes, Terry's death is foreshadowed; when she is seen staring at him, there is a picture of a bus in the background. Billy's death is also foreshadowed. While he is looking up at the plane taking off, the reflection of the plane is shown across his face. It is flying in a line right where the piece of the car decapitates him later in the film.
When Ms. Lewton examines the smoke coming out of her monitor, an image of a large dagger is seen in the background; part of the design in her door's stained-glass. It's revealed on the DVD commentary that this was a purposeful foreshadowing of how she'd be killed.