With the computers down they would of still said something like "we are accepting people for flight 5843 to Montreal" and normally they board one plane at a time per gate! The gate iteself still woulf of had a screen saying "flight 5843 to Montreal" right next to the door! If they took a bus to the plane like they do in Charolette for example the bus has the flight number and the destination on the digital banner. As for how secure a plane is supposed to be a person getting on the wrong plane is almost impossible unless someone didn't do their job! They have a list of every person on the flight and what seats they are sitting in. If someone was sitting in a seat that is supposed to empty that person is to be questioned and taken off if their info didn't match. Even with the ticket scanner down they should of still looked at the ticket before handing it in. This is the most bizarre story I've read! It's only because I worked in the airline industry before and this can get someone fired!