Getting on the wrong plane
How often does this happen?
My friend was booked to fly to Africa but got on a flight to Eastern Europe. None of the staff noticed, even when checking the boarding card. The card clearly stated an African city but it wasn't until the announcement was made by the crew that their flight time to Poland was ahead of schedule that they realised WOOPS.
Question of curiosity rather than being a 'check's need to be tightened moaner'.