This was my recent experience with an inner-European flight with an unnamed carrier: the plane was ready on time, which is notable.
A bus carried us to the plane and everyone boarded; then the steward noticed that the passengers had a different destination than the plane! So everyone had to disembark, get back onto the bus, which took us to the correct plane this time. We could have walked there faster, it was just in the next berth, but I guess airport regulations would not allow this.
So finally we taxied to the runway and were soon to take off, when there was an announcement that we had forgotten a suitcase and needed to go back to the berth. So we taxied all the way back, got the additional luggage loaded, had to wait for a new slot and eventually took off.
I had never before two hold-ups on the same flight, so this was extraordinary. But everyone laughed and was in a good mood, and we were glad that there was nothing relevant to safety going wrong.
