i’m trying to plan a film shoot, and it would be very helpful to have an overhead, doesn’t matter where it’s from

Is there any place in America/Canada (Britain would be ok too tbh) where you straight up can't move between cars while the train is moving? I'm writing a story where a character needs to get to the next car and was wondering if there is a place where the obvious solution isn't to just open the door even if it is illegal. Thank you!