I don't know, really

On a field trip with a group of people in Japan. Separated from them on the final day, just before we need to take the train to London. In a rush, stumble upon a Harry Potter-themed platform. Ask the ticket-seller if they go to London. They say yes and sell me a ticket.

On the platform, I discover the Harry Potter train does not go to London.

Change of plans, switch to a platform with a bunch of elderly heavy metal fans who are sympathetic that I was sold a bad ticket. Meet the tour guide from my original group. Decide to go to a local museum instead.