About the train

I don't think they would have gotten away from the train. They came back to get revenge, and to do that they were going to replay what had happend 27 years ago. The train got them 27 years ago, it was going to get them then, the only difference would have been if they killed Jimmy, cuz they would have killed him, and then train would have came for them. They couldn't escape the train, kind of like how Jimmy couldn't run away from them.

It wasn't exactly like the train was after them, but a simple re-enactment of the specific event. A train happened to be en route during the original tragedy, and thus it happened again. What surprised the boys was that a train was actually coming, even though none went through the town anymore. I think they were surprised that there was a "spirit world" counterpart, which made the re-enactment all the more real, even for the ghosts.

They wouldn't have gotten away, that was the whole message. Their restless spirits came back because they believed they died thanks to little Jimmy snatching their car keys. In other words, without the key, the car wouldn't start and they got struck by the train. This time around, they believed they would get the keys from Jim, kill him in retribution, escape the train, and finally be at peace. Obviously, the simple fact that Jimmy took the keys had no big effect on their dying, because as the re-enactment showed, they had no time to get out of the tunnel and away from certain demise.

And I don't think the 27 years had anything to do with it. It was the anniversary day of their death, and the only thing that was different that year was that Jim finally returned to their hometown. If he had stayed away, no doubt he would never have closure, never come to terms with his brother's death, and their spirits would forever be stuck in Limbo.