(at around 56 mins) When the song "Rocky Mountain High" is playing in Ms. Lewton's house, the audible parts of the song are not played in order.
At the memorial service, the speaker says that four teachers were aboard the plane, but earlier on Ms. Newton explains to the security guard that she has to be let back on the plane because the students will be alone. If there really were four teachers, two teachers still would have been on the plane.
(at around 58 mins) In the shot where Ms. Lewton pours hot water from her whistling teakettle, no steam is visible. Also, seconds later, as she is talking to herself, the kettle is visibly steaming.
(at around 59 mins) When the vodka is dripping through the coffee cup as Valerie Lewton walks to the computer, it drips onto the floor and leaves a trail of small drops. Later on, when the computer ignites, the small drops of vodka are a bigger trail.
(at around 39 mins) Clear's hair in the garage when she takes off her welding helmet is curled, then straight, then curled again.
(at around 19 mins) The plane exploding is too far away from the terminal windows to shatter them. Also, the time it takes for the windows to shatter after the explosion is inconsistent with the speed of sound given the distance.
(at around 1h 13 mins) When the train crashes into the Chevy Nova, the train keeps going. Accident protocol would be to stop the train.
The airplane exploding wouldn't have produced a shock wave powerful enough to shatter the glass window of the airport.
(at around 1h 20 mins) Downed power lines do not flail about wildly setting fire and explosions to all they touch. They lie perfectly still on the ground, occasionally setting small fires to grass, trees, etc, unless they land directly on a building or vehicle.
After Valerie Lewton throws out her tea, she pours cold vodka and ice into the mug, which causes it to crack and leak onto the floor and into the computer monitor. The sparks of the blown computer monitor ignite an unusually thick trail of liquor towards the stove, which is still on. Vodka averages 80-100 proof, or 40-50% alcohol content. Vodka, especially when very cold and diluted, isn't flammable enough to use an accelerant.
(at around 46 mins) Alex sees a reflection of a bus traveling in an impossible direction, but this is only a vision, not an actual reflection.
A flight leaving JFK International Airport for Paris could travel back over New York City, depending on wind conditions at take off.
(at around 43 mins) The deceased Tod moves his eyes while he is lying on the table in the morgue.
(at around 19 mins) When the plane explodes, the shadow of the plane can be seen still flying as the fire ball is falling.
(at around 48 mins) When Carter knocks Billy off his bike, you briefly see Billy in the distance riding his bike towards the camera; however if you look closely it is clearly not the actor (and presumably a stunt double).
(at around 15 mins) While the plane is in a nosedive, items can be seen falling down, toward the front of the cabin, as if the aircraft was still. The G-forces caused by a high speed dive would pull items up, toward the back of the cabin.
When Alex is in the restroom before getting on the plane you can clearly see his underwear while he is sitting on the toilet.
(at around 1h 18 mins) When Clear is looking at the picture of her and her father at the lake, the year says 1986. Since the film takes place in 2000, and Clear is 17, she would be a toddler in the picture, instead of being between six and eight years old.
In the alternate ending on the DVD, Clear has a photo of her and Alex where one of them is holding a white rose. This is the photo taken from the beginning of the movie, but the position of the photo is not the same angle that the photo was taken from.
When Alex and the rest of the French class are getting on Flight 180 Alex looks down and sees a airline service vehicle with the number 666, However airline service vehicles are not allowed to drive under the Jetway.
(at around 10 mins) When Alex pushes Tod shortly before boarding the plane, Tod says "Ow that hurt". But when he says "That hurt" his mouth is not moving.
The camera's reflection is momentarily visible in the reflection of Tod's mirror when he's in the bathroom.
(at around 56 mins) When Ms. Lewton is lighting the gas under the kettle, reflections of three lights can be seen in the kettle. No kind of practical lighting is present in the next shot which could have created these reflections.
(at around 1h 12 mins) Although this film is set in New York, the train that smashes Carter's car is a "BC Rail" train, which only runs in Canada.
(at around 1h 10 mins) As Carter's car arrives at the crossing, a blank white crossbuck sign with a red border is seen. This is how the signs look in Canada (where the film was shot), but in the U.S. the signs say "Railroad Crossing".
A Panago Pizza restaurant can be seen down the street from the café where Alex and Clear are. There are no Panago Pizza locations in the U.S.
(at around 25 mins) The newscaster said after the crash that the group consisted of 40 students and 4 teachers. This means that during the scene where they all got kicked off the plane, there was no reason for the conversation between the two teachers and the airline worker about how one of them had to get back on the plane to watch the students. There were already two other teachers on board, so the French teacher who went back on the plane in actuality would not have had to die.
It is stated that the characters die off in the same order they would have died in the airplane explosion. Alex traces the death order by following the path of the leaking fuel toward the source of the explosion. However, the explosion would have gone in the opposite direction, away from the source of the explosion. As such the characters are dying in reverse order.
(at around 27 mins) During the memorial service at the high school, the speaker says that 39 students and teachers were lost. But there were 40 in the class, with four teachers, and seven people got off the plane so it would be 37 people who were lost on the plane.
(at around 1h 25 mins) When Clear is in the car that was being attacked by the electrical wires, Alex said that the car was "grounded by the tires". This is incorrect as the rubber tires are actually an insulator, hence they do not complete the circuit (for example, ground the car). Also, the car should act as a partial Faraday cage, which means that all of the charge would be on the outside surface of the object (in this case the car), and that the person inside would be safe.
(at around 6 mins) At the airport, the French teacher addresses the students with "écoutez, les enfants!", which means "listen up, children". No French speaking person would ever address 16-18 years old with "enfants", "enfant" meaning a (little) child up to perhaps ten or maybe twelve years at the most.
(at around 47 mins) When Alex and Clear are discussing Death's design at the coffee house, Alex refers to Valerie Lewton as "Mrs. Lewton". She's called "Ms. Lewton" throughout the film and there's no sign, nor mention of a husband.
Billy mentions at the memorial that he got a 70 on his driver's test, but there is one problem with this. The DMV doesn't give you a score when you take your driver's test, they just tell if you pass or fail, so this makes little sense and is not explained very well.