Factual error: When initially investigating the missing people and the condition of the airplane, Brian looks at a screen that gives the airplane's transponder code (or "squawk") as 7777. An airliner would never be squawking that code, since this particular code is reserved for military interceptor operations.
Continuity mistake: In most scenes at Bangor airport the plane (L1011/Tristar) can be seen in the middle distance from the terminal window, but in one or two scenes it's right outside blocking the view.
Factual error: When Nick "turns the pressure back on" all he does is flip his O2 regulator from normal to emergency. This would not have helped the other passengers wake up. (02:46:20)
Other mistake: When the passengers are frantically trying to refuel the jet at the Bangor airport (and Toomy is having a psychic/psychotic meltdown), everyone's attention is drawn to the collapsing power lines in the distance as the Langoliers head straight for them. Up until this point, we have been abundantly reminded that there are no odors, no sounds, no living things, no nothing except sterile, inanimate objects in the past, so the plane passengers are the only living, animate beings in this dead zone. However, as everyone looks toward the Langoliers in the distance, a flock of very animate white egrets (cowbirds) rise up from the grassy meadow in the foreground and circle once or twice for the camera.
Other mistake: Towards the middle/end the mystery writer specifically says that on the airplane in Bangor there is electricity but in the airport there is none. However, when first arriving at the airport you can clearly see there are lights on overhead.
Continuity mistake: Albert knocks Toomey out with a toaster. You can see during several subsequent shots that there is only a small amount of blood on Toomey's forehead and none at all on his face. Toomey lies there unconscious for a while, without changing position, and when he wakes up, suddenly his whole face is cut up and bloody. (01:54:00 - 01:59:05)
Factual error: Attempting to steer an airplane moving along the ground at more than 100 knots will cause the landing gear to be destroyed.
Other mistake: When Toomey looks out the airport window toward the plane, there is an airstair unit rolled up almost against the aft right side of the airplane in front of the horizontal stabilizer. The airplane didn't taxi (not could it) to swing past the airstair unit. The wing wouldn't have cleared it. (01:06:25)
Other mistake: Aircraft door is closing, aircraft is going underway. The roll up stairs are still on the side of the aircraft, I used to fly the L-1011 for a living, the side air stairs would cause a bit of damage to the leading edge of the wing. Next scene shows aircraft underway and no air stairs and no the target style engine reversers weren't used in this situation (these aren't clam-shell style as the other writer has probably seen on the arc-9/MD80 series aircraft), there would be a lot more noise and turbulence. (02:15:00)