Continuity mistake: The captain gets shot. The copilot is still in the right seat when requesting emergency landing (first landing). In the landing, someone's hand from the left (captain's) seat is moving the throttle controls yet the copilot's leg is visible (and moving) in the right seat. The copilot stays in the right seat when the plane departs again. (00:42:20)
Continuity mistake: As Cutter rides away on the motorcycle, a wide shot of the plane shows the doors are closed and the release of passengers has finished. However, when the FBI arrives a minute later, passengers are again being released from the plane. (00:50:00 - 00:51:10)
Continuity mistake: After the FBI agents who escort Rane up the boarding stairs are shot, Rane runs up the remaining stairs and past Mr Forget. 2-3 seconds later there is a wider shot of the plane which again shows Rane running up the stairs and past Mr Forget. (01:04:35)
Revealing mistake: When the terrorists drop the dead body out the aircraft door, look closely at the aeroplane just beneath the door, you can see the reflection of the mat the stuntman lands on, as well as the spotters around it.
Continuity mistake: Liz Hurley shoots one of the FBI agents seated next to Rane, in the background the other agent can be seen with make-up on waiting to be shot next. Then the angle changes and his blood has vanished.
Continuity mistake: A sexy blond woman wearing a short hot-pink top, dark jacket and miniskirt exits the plane with the first 100 hostages. She leaves again later with the rest of the passengers and is seen leaving the plane again at the end when the members of the press surround the plane to question the agent.
Other mistake: In several of the scenes involving the helicopter the film was flipped. The registration numbers on the side of the chopper are backwards.
Continuity mistake: You can tell what order the scenes were shot in simply from the condition of Wesley Snipes' face. The actor obviously had a horrible skin problem throughout the film production - his face is riddled with acne and boils. When watching the film, keep particular attention to the right side of Snipes' face (in fact, many scenes are shot in order to avoid his right profile) for huge boil on his cheek - it keeps appearing and disappearing throughout the movie. Furthermore, you can even tell what scenes had to be reshot because the unsightly blemish appears and disappears even within the same scene.
Continuity mistake: When Wesley Snipes is brought down the control tower steps by the two cops, he is wearing handcuffs in the control room and then the handcuffs disappear when he throws the cops down the stairs.
Factual error: When the aircraft window is shot out, depressurization of the plane occurs shortly after the door of the plane blows off. When depressurization occurs, the pressure in the fuselage drops. Why would the door blow-out now when it held before with higher (normal) pressure?
Continuity mistake: When Wesley Snipes beats up the two cops hauling him down the stairs of the air traffic control tower, one cop's hat falls off. In the next shot of Snipes knocking him down the stairs, the hat is back on.
Continuity mistake: One scene takes place supposedly at a county fair in Louisiana. Louisiana doesn't have counties, they have parishes.
Factual error: When the large airliner is brought down at the the small, regional airport, a huge movable stairway is rolled up to the aircraft so that people can disembark. There is absolutely no reason why a stairway designed for major jet aircraft would be sitting at a small airport that didn't even have runways long enough to accommodate such large airplanes.
Audio problem: When Cutter rolls and shoots at Vincent, we can hear the distinct sound of his pistol. However, we see a shot of the pistol's slide in the open/locked position, meaning he's run out of ammo, but we can still hear the pistol being fired a few times after that.
Continuity mistake: After Cutter crashes through the fence, you see the black box with the antenna that was sitting on the back of the motorcycle fall off. When he gets to the fairground, the black box is back on the back of the motorcycle.
Continuity mistake: When Charles Rane runs away from the police at the start of the movie, he shoves a guy in a brown suit over, but in the next shot the guy has now completely disappeared.
Factual error: Just after Ranes shoots a hostage, when in the standoff with Cutter, the pistol (a Beretta semi-auto) is shown uncocked, which wouldn't happen normally since the movement of the bolt after the shooting to eject the capsule also cocks the guns automatically.
Factual error: The L-1011 lands at the small airport and the hijackers demand fuel. When the fuel tanker shows up with the fuel, the fueler opens the fuel panel and puts an 'overwing' nozzle up inside the fuel panel. This type of nozzle would only be used if the fueler was on top of the wing filling the wing through a small gas-cap type of fueling point.
Factual error: First, when Raine fires his gun and blows out a window, it causes explosive decompression which results in a door being blown off. It has been proven (Discovery TV's "Mythbusters") that explosive decompression does not result from a gunshot hole. The plane would, of course, lose pressure, but slowly. Even explosive decompression would not rip a door off its frame. Second, with the plane decompressed, Cutter and Raine (and everyone else) would have passed out within 15 seconds from hypoxia. It's funny that not a single person in view of the cameras actually put an oxygen mask on. Third, as soon as decompression was detected, any well-trained pilot would have put the plane into a dive immediately to get it below 10000, so that passengers wouldn't die. It is interesting that even at the end of the fight, as we see Raine falling to the ground, the plane is still flying straight and level at altitude.
Character mistake: When Cutter is talking with Chief Biggs for the first time, right after the negotiations for fuel, Cutter says he is the former head of security for the airline. Since he has just been hired for that role (after being an independent security consultant), he should have called himself the future head of security, or new, or something of that nature. Former would indicate he has resigned from the position.
Answer: It's been a while since I've watched this movie, but he obviously knows the plane is hijacked. It's a pretty safe assumption that the agents are dead as they're escorting a dangerous, high profile prisoner. Pretty easy to connect the dots. Alternatively, they could've failed to check in, and he assumed the worst.