Continuity: After the train comes to a complete and lurching stop, the porter is shown being thrown forward into the bad guys as a lot of baggage falls all over the place. In the final fight scene as Ryback is entering the dining car, all the tables have all their place settings perfectly intact.
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Mistakes
During the scene where Ryback is fighting Penn (the grey-haired mercenary) in the kitchen, watch for the shot where Ryback flips Penn. The film has been sped up and the result looks disjointed and out of place. The characters are moving FAR too fast for it to look natural. See more...
Under Siege 2 mistakes
Plot hole: Now why the heck is one of the stealth fighters anywhere near the train? Stealth fighters use advanced targeting and do not need to be anywhere near their target, yet in the movie the one fighter is so close to the train when it gets blown up that it looks like it's on a collision course.
Factual error: The footage of the "Nevada Petrol Express" actually is of a similar operation that used to run over the Tecahapi Pass in Southern California. And "Espee" terminology never had "Petrol" in its language.
Under Siege 2 trivia
When the satellite destroys the fertiliser plant in China we see a 2 second shot of a steel tower collapsing into a ball of flames. This exact shot was used in one of Steven Segal's other films: On Deadly Ground.