Revealing mistake: Look for the blatantly awful special effects when the main bad guy is falling into the flames.
Continuity mistake: This happens when they stop the train in order to get the CD that was confiscated by Steven Seagal. A moment or two after the train comes to a complete stop, Travis Dane explains how important the disc is - if you look behind him you can see the scenery outside the window still moving very quickly.
Audio problem: At the beginning of the movie, the terrorists start take over the train, Ryback beats up a terrorist and throws him out of the train then some guy says something into the radio like, "we got one casualty", his mouth doesn't match what he's saying.
Revealing mistake: When Ryback is fighting the grey-haired bad guy in the kitchen, the bad guy is losing and spots a meat cleaver on the counter. When he quickly picks it up, holding it at head level, you can see the cleaver blade wobbling from side to side. An obvious rubber prop.
Factual error: The film's plot violates the third of the Ten Immutable Laws of Security by Scott Culp. The premise of the law is: When one has physical access to a computer system, given enough time, he can take over the system. In the film, the reverse happens: Dane takes over an ATAC site remotely while people inside (who have complete physical access) cannot do anything to wrest the control back. In the real world, it is usually possible to simply cut the connection cable or antenna and take control back. (Even Windows XP and later have such simple lockdown provisions as part of Windows Firewall.) After the lockdown, the passcodes can be changed and other measures taken.FleetCommand
Factual error: The main premise of the film is ATAC's loss of control over their orbital weapon and their attempt to prevent it from doing damage. According to ATAC, they needed to know where the weaponized satellite is, so that they can lock onto it and send it a self-destruct order via radio waves. This isn't how the real world works: Radio waves emit in all directions from its transmitting source. The location of the satellite need not to be known; only it must be within the reach of the ATAC's signal.FleetCommand
Continuity mistake: When Captain Trilling enters the room where Captain Gilder is waiting for him, she says "Have some champagne, Captain Trilling." When she says this, she has the wine glass in her right hand. A split second later, as Captain Trilling gets close to her, she has changed the glass to her left hand. There was not enough time for her to do that, especially lying on her side like she was.
Continuity mistake: When they decide to use the second Pegasus missile, the guy with the glasses says that they still have eight possibilities left. The Admiral tells him to pick one. He is about to pick Delta, then switches to Kappa. In a previous shot that shows the large screen with all of the remaining satellites, when the guy said that there were still eight left, the Kappa satellite is not there.
Character mistake: After Ryback was allegedly killed, Penn claims "we got him, but the SOB killed six men." Penn would not have known this, as he was with Dane the whole time preoccupied with Dane and his plans - he was nowhere near all the killings done by Ryback and never checked with his men at the time who was still accounted for. Also, it appears Ryback killed much more than just six by then anyway.
Visible crew/equipment: When the bad guys steal the helicopters and take off you can see the blades spinning at the top of the frame from the camera chopper during the wide shot of the other two choppers.
Other mistake: After Dane says to Penn "They'd shoot all the hostages", he says something additional but there is no sound - just his mouth moving from the side view as the camera pans to Penn's face.
Factual error: The terrorists supposedly stole the helicopters from a fictitious National Guard Base near Leadville Co. (No such base exists), but when they take off in the helicopters you can see the eastern slope of Pikes Peak in the background. Indicating that the helicopters are taking off from an airport just east of Colorado Springs.
Continuity mistake: The 2 captains are thrown out of the train into the river under the bridge. Later on, when the shooting starts in the hostage's cars, they're back and one captain is shielding the other.