Edit: apparently this is a very common form of Japanese storytelling called an isekai. There are 8 billion people in this world, no idea can be original. And sometimes you miss out on things many other people know. I’m clearly one of today’s lucky 10000.
I would be shocked for sure but how would I know how to react if I don’t know what this new world is like? Does it look like a barren wasteland? Does it look like Dinotopia? Does it look like a different planet altogether? When you say ‘unknown’, is it unknown to me only or do you mean it’s completely devoid of any civilized/intelligent species?
You look outside the train window and see what looks almost exactly like a forest on Earth, maybe something like redwoods, except the trees are much bigger than redwoods. A horse-sized dragonfly flits by. The front of the train carriage is crumpled, but there is a gash in the metal big enough to allow you to leave, if you desire, and to let the atmosphere in. You don’t feel any ill effects.
Okay, so I’m shocked and after a while I’m definitely hopping out of the train, presuming no emergency services show up. I don’t think I’ll last long if dragonflies are that large but I sure will die looking for them