Factual error: In the shot where the lady passenger boards the Upper Deck to take her seat, she boards through an aft-facing straight staircase, located at the rear of the cabin. On the 747-200, which they were flying, the majority were equipped with circular staircases, and a few equipped with the aft-facing straight staircases, but in both cases, they were located in the front of the cabin, no exceptions.
Continuity mistake: When the fighter shoots and blows up the truck, there is a shot of the flight attendant (at that moment being strangled by Ray Liotta) sitting in the pilot's seat, looking over her shoulder. It cuts back to the pilot, then back to her being strangled again. Very, very choppy editing.
Factual error: In the shot(s) where the flight attendant approaches the cockpit, it shows an emergency exit door located on the left hand side of the cabin, however on the 747-200, which they were flying, the emergency exit door is located after the cockpit door, and is approximately 1/4 the size as shown. The door shown belongs to a 747-300/400 upper deck door, located in the middle of the upper deck cabin.
Continuity mistake: When Lauren Holly's character boards the plane she shows Catherine Hicks her bare, ringless hand, meaning that she broke up with her fiance. Two seconds later you see Lauren Holley in a galley-type closet thing taking off both her leather gloves. There was absolutely no reason for her to have put the glove back on.
Deliberate mistake: In a lot of the shots in the cockpit, when Teri is attempting to begin taking control of the aircraft, notice the Horizontal Situation Indicator on the First Officer's side. The compass rose is moving around erratically - which would suggest that the 747 is also changing heading extremely erratically and robotically - which isn't possible.
Continuity mistake: Near the end of the film when Lauren Holly is learning how to land the plane it is raining outside, but in several shots from the outside of the plane the camera pans up slightly...to reveal the jagged edge of the flight deck window. Now I'm no plane expert, but if the window was broken, she would be being pushed back by the force of air moving at 500mph. It seems it's only there so the shot of her is not distorted by the rain, but the camera leaves the jagged edge in the middle of the screen, so it doesn't even look like the camera is just inside the window.
Continuity mistake: Very soon after that, when Ray Liotta is trying to grab the stewardess, we see a shot of the two of them on the floor, and the stewardess is clearly fiddling with the gun, trying to get the bullet in. Then in the next shot, her hand is further back, and she's reaching forward for the bullet again.
Factual error: After the 1st aborted landing on 25 left (250°, left runway) the flight attendant is asked to land on runway 7 right (The same runway but in the opposite direction, 70°). The aircraft would need to turn to the east to get onto the new heading of 70°, but the shot on the tower screen shows the aircraft turning onto a track of 270°, taking it off over the ocean. (01:30:00 - 01:31:00)