Well..

[ Madoka really doesn't like looking at it from that point of view - no matter how realistic it may be. Hence why the girl is starting to look a little awkward as she's thinking about it. Yet she doesn't want to dismiss Raven either, so.. ]

Maybe they just realise that if something would happen that'd be bad enough to destroy a part of the train, it'd have really negative consequences for them too.. [ They're all stuck on it, after all. ]