The device Ryback connects to the disabled phone is an Apple Newton PDA (personal device assistant) MP2000. This device, about the size of a iPad mini and the thickness of a book, was used for notes, calendar and calculator. It did not text or email. It also ran some 3rd party software like Quicken.
Although the Pegasus missile shown in the film is functionally similar, it bears no resemblance to the actual rocket. In real life it features a low profile delta wing in the middle with a traditional vertical and horizontal stabilizer at the rear; as opposed to the 8 fin air-to-air style missile launched from the B2 bomber.
Filmmakers pioneered a new technique that enabled them to film all the interior train scenes (practically all the film) in the studio. Tennis balls glued on the studio walls were used as reference points to allow computers to insert footage of Colorado scenery, even when the camera moved around.
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.
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.
What are the differences between the British BBFC-18 home video version and the uncut version of this movie?
A
The British BBFC-18 home video version has been heavily cut in order to obtain a rating and several action sequences involving knives, bone breaking and other cruel violent scenes are missing in this version. A detailed comparison between both versions showing the visual differences (but not the sound cuts) can be found here.