On first time, I think that the story about Kumiko is perfectly possible. Of course it's a funny story but I think it's quite easy you take a wrong turn and you don't realise until some hours have passed. And still more! how many times anyone of us hasn't turned on a wrong train, or hasn't taken a wrong turn driving, etc. Maybe in this case the most strange is that when Kumiko got off the train she really thought she arrived in the right country. But again: I can imagine myself on the same situation!!. Furthermore when you are in a foreign country you get absolutely and completely lost, sometimes you not even know where your right hand is.
On the other side, in my personal experience, now I can't remember a misunderstanding due a bad pronuntiation. In fact, I try and I try it again but all I'm able to remember are misunderstandings with women for something I've never said. Something I said a lot of time ago but that now it's impossible for me to remind. Something I should have said but I didn't. Or something I said but was misunderstood.