Goofs

When the train is stopped so the mercenaries can retrieve the CD, after the train is shown slowly reversing backwards, we see Dane talking to Penn. Behind Dane there is a window showing the train is still moving, and fast.

When he shoots down the Stealths, Grazer 1 HAS to be somewhere between Denver and LA. It is directly above the train. There are no satellites on that path. The satellite path for Delta comes down through Canada to Washington. and nowhere near the train's path.

Wine glasses are still standing after a deceleration powerful enough to throw people around.

When ATAC chooses to fire their final Pegasus missile, there are still 10 ghost satellites remaining, plus Grazer's actual orbit. Of these 11, Gamma is the only satellite above US soil. It turns out not to be Gamma.

After recovering the CD from under the train, Penn says to Sarah, "Guess your uncle wasn't that good after all." But none of the bad guys has yet established the exact connection between Sarah and Casey, except that Sarah is traveling as Casey's '+1' on the passenger manifest.

While Ryback is hanging on the rope, the porter takes a few pot shots at the terrorists. Prior to shooting he says, "Safety off". Glock handguns do not have a safety that can be switched on or off. It is integrated into the trigger assembly and turns 'off' as the trigger is depressed.

Several times Ryback opens panels on the outside of the train. When they are hinged towards the front of the train, the air rushing past should blow them back against the side of the train; if the hinges are at the back then the panel should fly open. Neither of these actions appear to happen. Only much of the train footage was shot live on location and the real world physics prove that it is possible,

During the final train collision, all of the Southern Pacific locomotives of the Nevada Petrol Express are shown with their head lights fully illuminated. Only the lead loco should have its lights on.

In order to defend herself, Sarah Ryback sprays Marcus Penn with a non-lethal spray, and says "[This is] Mace!" The spray has little to no effect on Penn, who then responds by saying that it is "Not mace, sweetheart. Pepper spray. Sold to civilians. But once you get used to it, it just clears the sinuses." Pepper spray is actually much more effective than the classic Mace (brand name). Penn, as a highly trained mercenary, should have known the difference.

Travis Dane pronounced 'Guangzhou' incorrectly. He prounces it 'Gwan-zoo' It is actually pronouced 'Gwan-joe'.

When they take over the train, Ryback beats up one of the mercenaries, either killing him or knocking him unconscious, and throws him from the train. Another mercenary says over the radio they have a casualty. Despite this nobody seems concerned or suspicious about what happened to this mercenary, and sensed there may be someone aboard the train trying to thwart their plans. However, the car is full of cooks. The assumption of the mercs was that one or all of them overpowered him then threw him out. When they shot up the car they found plenty of dead bodies and assumed they were the culprits since that's who they found. They had no reason to assume there was anyone else involved.

After Dane receives the passwords from the agents, he then enters them onto one computer using two keyboards. This would actually work since this is how it operates at Grazer Control and his equipment on the train are duplicates, or upgrades, of the Grazer computers.

It is absolutely impossible, even for trained people, to keep your hands behind your heads for hours and hours. Yet this is what we see with the hostages in the train whilst the action goes on.

In some of the shots where characters are pursuing each other on top or the side of the moving train, their clothes and hair are not blowing in the wind.

When the second stealth bomber explodes after being hit, the model of the bomber can still be seen clearly swinging on wires at the top of the shot.

When Ryback kicks a terrorist off of the front of the moving locomotive, it's an obvious dummy landing on the tracks when seen from the high wide-angle shot.

Shortly after attempting to send the fax from the payphone, Casey is seen pulling a dead mercenary through a door by his arm, shortly before another mercenary comes down the stairs. Casey grabs the dead guy's left leg to pull it, but both legs move together as the actor moves them himself.

The actual credits for this movie show that Dale Dye played Col. Darza. This is incorrect in more than one way. Not only does Admiral Bates call him Captain Garza in the movie but his character is a continuation from the first Under Siege (1992). On a more factual basis, Colonel is not a naval rank and Captain Garza wears a Naval uniform.

When the UH-1B helicopters are being hijacked from the military base, a view of the instrument panel shows the registration number N234SJ. Military aircraft do not have N-number registrations, only civilian ones.

Bobby uses the dumbwaiter elevator to travel between levels of the train, yet the elevator door is clearly labelled with a capacity of only 25 pounds.

When the female mercenary shoots Ryback thru the sniper rifle the problem with that scene is that they had been hunting Ryback on the train for quite some time and now that they had him in plain view only a shot to the shoulder was he hit by seems to me that these mercenaries were very sloppy and inexperienced or they just could not aim and shoot correctly to deliver a kill shot on a target..

When Casey is on top of the train car looking at the terrorists through a window on the edge of the roof, Travis Dane says "300,000 pages of code. Or 60 minutes of triple-X rubber-and-leather bondage porno.", his mouth is clearly not moving.

When the bad guys are loading the equipment on the train, one of the bad guys says, "trouble in the dining car, one casualty." But his voice obviously doesn't match his mouth.

When Herb, one of the Mercenaries threatens to kill a child, his mouth is closed, but you still hear his line.

Rotor blades of chase helicopter visible when Hueys are leaving the National Guard base.

When the merc is climbing up the front of the lead locomotive, the safety-cable supporting him from an overhead crane is fleetingly visible in one shot as dancing white dots directly above him.

Dane was threatening to blow up Washington, and was using his "ghost satellites" to hide the weapon's location, but since he had made clear the target, his satellite would have needed to position itself over the capitol, so that would have theoretically given the government a chance to locate his satellite visually (rather than just relying on computer tracking systems) and destroy it before it could destroy them.

Why didn't Bobby destroy the CD when he took it out of the PC reader? Even if he didn't know what it did, destroying it would have been the smart thing to do.

If the computer was down since Bobby stole the CD, the targeting would be off and the ghost satellites would be missing allowing ATAC to find Grazer-1.

The young computer operator says, "It was Delta!" when he sees which satellite remained after the "ghosts" disappeared. Yet the one remaining was clearly the one marked OMEGA.

With all events taking place in the continental US, Admiral Bates as Chairman of the Joint Chiefs should not be in charge as he has no command authority. Commander-in-Chief Atlantic Command or Joint Forces Command should take command.

A well prepared terrorist like Dane would have multiple copies of a CD with crucial codes so that if one of them got lost or damaged as seen in the movie, it wouldn't compromise such a high stakes mission.

The bar tender is shot in the knee for complaining while Rybak's niece is taken away but on the other hand a female passenger is let to go to the bathroom and she is applying lipstick (in a hostage situation) while Ryback comes out from the ventilation.

Ryback remarks to the cooks, "Because the train is rocking, it's cramping my style." Yet in Under Siege (1992) he was a culinary specialist on a warship that rocks when changing speed and in different sea states.