Every self-respecting Prague resident loves watching tourists struggle to exit public transport.
Prague transport, all of it actually, is designed so that sometimes you need to press a button to open the doors for entry/exit. The button (Czech: "Tlačítko") is usually located either directly on the door or somewhere near it.
You don't always need to press something to exit. During rush hour, the driver will most likely open all doors automatically.
But when you absolutely must press, it's when there are request stops on the route. Usually this happens only on buses, but I've seen it on trams too.
The conclusion is simple - if the evil Czechs have decided not to let you out of the bus or metro - look for the tlačítko, it's politically neutral and will definitely help you.