Have you ever been in an argument where you absolutely objectively proved you were correct?

An ex and I were on an hour-long bus trip to the next city over where we lived in Korea. The subject of there being a subway in said city came up, and I insisted there was not. She insisted that she saw one there once. I further insisted that there was no way the city was big enough to have a subway. It got quite heated. Anger. Hurt feelings.

She was talking about the sandwich restaurant, I was talking about underground trains. We were both right.