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.
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.
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.