Feeling like an idiot, part 2

A while back I had a post entitled "Sometimes being a foreigner means feeling like an idiot". Consider this the second installment.

We had wrapped up a good weekend in Berlin and headed to the train station to catch our train back to Hannover. We went up to the platform and sat on a bench to read and wait. At about the right time for our train to arrive, both Brian and I heard an announcement for the train toward Hannover Hauptbanhof (main station), our destination. He grabbed our suitcase and headed toward the train, and I followed. We had assigned seats but didn't see the number of the train car we were supposed to be on. That's when I looked at the video screen by the door and realized that the train was headed to Frankfurt! "We are on the wrong train," I said in a voice that I thought sounded calm but I am sure has some undertones of panic.
The doors had just closed and I kept repeatedly pushing the button that I hoped would open them. The problem was that this was an express train and we had no idea when those doors would open again.
Brian led the charge to the other end of the car to try and find a conductor who could open them for us, and then the train started to move.
We did find a conductor - a woman with multiple piercings and a bright yellow streak in her hair that said apologetically (in English) that we couldn't get off until the train reached Braunschweig. I had never even heard of Braunschweig. We found a map as we stood there - me sort of stunned and Brian muttering swear words under his breath - and saw that luckily Braunschweig was just southeast of Hannover. When we had calmed down a little I asked the conductor again what we needed to do and learned that we could catch a local train from Braunschweig to Hannover. So in the end we got to Hannover just 30 minutes later than we would have, feeling like idiots but safely back home.