I have noticed that any time I play as a passenger and take a seat on a train, then change to the external camera, then try to go back to first person it glitches. It means you cannot control anything anymore and it's also impossible to fast travel out of the train even when stopped. This is a TSW6 bug on all routes.
I guess nobody has played or plays as a passenger from time to time in this game judging from the feedback.
