Bullet-train would be good....because it's speeding along the ground, and you could emphasize Superman's high-speed flying better with more objects whizzing by....buildings, trees, through tunnels, elevated tracks (hopefully not too Spiderman II)...better physical dynamics than in the open sky, and a lot of large obstacles that he has to weave in and out of....using shots from inside the train car seeing Supes flying along outside the windows, etc.
But instead of stopping the whole train at once from either end...which would likely cause the multiple cars to fold up around eachother of tear off inpieces....he has to do it in sections, one car at a time....severing the links with heat vision, safely slowing that car down so as not to put too many g-forces on the occupants (thing's traveling at over 200+ mph, after all). Then he has to catch up to the rest of the cars that are speeding away, and so on over the course of miles....with each car and section of track presenting different obstacles....tunnels, raised tracks, nearby buildings, etc. But by the time he's ready for the last car....in this case the front car since he goes from the back forward...it's nearing the end station with a dead end. Not enough room left on the tracks to slow it down without it squashing upon impact. So in a split second, he zips over to the end of the track barely ahead of the oncoming last car....rips the track from the ground and the 'end pin', and lifts them up in the air so it's a ramp, which sends the car flying like a javelin hundreds of feet in the air.
Then he simply catches it and brings it floating back down to Earth. There's your rescue scene.
See...if they end up doing that, it's already friggin' spoiled for us.
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