The crew was told? Who "told" them? The contract Dispatcher, Ground Ops, the crew desk? Questions should have been raised well before the plane left the gate. Was there maybe a last minute; crew change, gate change, plane change etc., that contributed to the 'mix up?" That's not mentioned, but you have to wonder. If the crew boarded through the terminal, what did the gate signs say? Do they ever notice all the handle tags on the luggage, or maybe look at an airbill when they're on the ramp? Simply saying they "flew the plan as intended," is just trying to rationalize what happened. All the passengers "intended" to deplane at Dusseldorf! The company obviously intended that to happen too.