Factual error: The Russians stopped using steam locomotives in the 1970's. So bringing one out of retirement in 1997 to haul nuclear warheads would mean that your highly secret nuclear train would be well known among rail enthusiasts for weeks before.
The Peacemaker (1997)
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Directed by: Mimi Leder
Starring: Nicole Kidman, George Clooney, Aleksandr Baluev, Marcel Iures
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Thomas Devoe: I don't know about these guys, but General Aleksandr Kodoroff doesn't ride around on a nuclear transportation train. It's like Ivana Trump on the subway.
Question: Wouldn't they know something was up when the train explosion wasn't as huge as it should have been (because many of the bombs were missing, and thus making the explosion smaller)?
Answer: The two train engines colliding caused the explosions, all the other cars derailed. All the warheads were carefully packed and disarmed.