One evening in the days of paper tickets and a seat-assignment sticker on the ticket jacket annotated with the flight number was your boarding pass, when dinosaurs roamed the earth, I was flying DTW-PHL on NW. As we were taxiing out, when the FA announced that we were on flight xxx to PHL, there was a murmuring in the back. Turned out two rather elderly ladies wanted to go to DCA, which flight left from the gate next to ours. So we turned around, returned to the gate, and the ladies came forward to leave the plane, accompanied by tremendous abuse from the crowd of businessmen wanting to get home for the weekend. In those days I imagine GAs didn't pay much attention to the flight number or destination written on the jacket, only that you had one.

I suppose incidents like this were the reason for the FA announcements during boarding that "this is flight 666 to Providence".