Factual error: Later in the movie when Mrs. Lewton is playing John Denver's Greatest Hits, there's two things wrong with the scene: Rocky Mountain High plays as track 1, but is not the first track on that album; second, the song is out of order. The line "but the string's already broken, but he doesn't really care" is repeated twice before her death.
Factual error: When the teacher gets killed, the vodka on the floor catches fire, and there's still enough alcohol left that the fire follows her? I don't think so - vodka will burn, but not that well.
Continuity mistake: Late in the film, Alex Browning hides out in the cabin and attempts to make it as death-proof as possible, securing everything therein with ropes and duct tape, and carefully placing his kerosene lantern in a tray of water. At first, we see that the antique lantern is painted dark green; but, one scene later, the same antique lantern (in the same tray of water) is now painted bright red.
Continuity mistake: In the scene where Billy gets his head sliced off by a piece of metal that fell off the train, as his head rolls away his hair is a much lighter shade of brown than it was during the rest of the film.
Continuity mistake: When Alex is talking to Clear in her garage, one strand of her hair keeps changing, first curled under, and then straight, back and forth...
Continuity mistake: Near the beginning, when they are at the Memorial for the school, look closely to the right of Devon Sawa right after he and the other gal look at one another - an extra with red hair walks in front of him, in the very next shot Devon gets up, and the same extra is now behind him.
Continuity mistake: When you see Alex watching the news report about the crash of 180, after coming back from the airport, you see his mum and dad asleep on the couch with a pillow at the end of his mothers foot and a few shots later after hearing the loud thunder, the pillow is lying on her ankles.
Character mistake: In scenes following the plane crash, authorities refer to the 'National Transportation AND Safety Board.' The organisation is called the 'National Transportation Safety Board' - no "and".
Other mistake: When the plane takes off in Alex's vision, the plane begins to go into a nosedive, and the entire left fuselage is blown apart, sucking many people out of the plane. The plane then explodes completely, but in reality, the plane just takes off, and explodes almost instantly afterwards. No struggling with the plane is shown in reality, nor is the plane going into a nosedive. This is also proven in FD5, which is a prequel. The jet engine explodes, leaving a flaming tail, and the plane spinning out of control. The plane just simply "explodes" without any signs of struggle.
Character mistake: The scene where Clear is trapped in the car and Alex is trying to save her, he incorrectly tells her the tires are grounding the car and to not touch anything. Rubber tires insulate the car preventing the charge from reaching the ground. If Clear were to get out of the car touching metal on the car and the ground at the same time she could be the conduit for the charge to pass through. (01:25:50)
Continuity mistake: After Alex reads his porno and throws the magazine at the owl, that one piece of paper with "Todd" pops out of the fan after the magazine got stuck in it. Now, this is a very small mistake, but if you look at the shape of the piece of paper, the one short stump side changes between takes. Like I said, it's very small differences, but there are differences.
Continuity mistake: A reporter takes a photo while Clear and Alex talk at the memorial. When we see the photo in the article, it's at a different angle and Alex has vanished from where he should be next to her.
Continuity mistake: Alex buckles his seatbelt when he first sits down on the plane, before the girls ask him to move, making him have to unbuckle to move for them. When he wakes up after his premonition, he immediately jumps out of the seat, not buckled in.
Plot hole: During the premonition, Carter and Terry are sitting directly next to each other. However, we know that before Carter dies, both Terry and Lewton (who is sitting 2 rows in front of them) have to die first. When Alex sees the report that marks the explosion path, it suggests there is a chain reaction that goes from Tod's seat to Terry's, and then Lewtons. If this is true, should Alex have not died with Tod and Carter with Terry? Tod can actually be seen getting hit in the head with somebodies luggage, and if this is how he died, the news report suggesting a 'chain reaction' is wrong; Tod's seat never explodes. Can anyone tell me if the drawing Alex did with the line going from seat to seat (before the explosion) is not supposed to be an explosion? If you slow down the premonition, both Terry's seat and Lewton's seat blow up about a split-second before the explosion erupts - this is possible but the distance of one of the explosions from Lewton is larger than the explosion from Carter.