Just as an example of misidentifying an aircraft, only today I was looking at the clouds and perhaps several miles away taking off from London City airport was a swept-wing aircraft that for about 20 seconds looked like.....Concorde!!! (but without winglets)
Really, the perspective and angle just made the shape, but then it banked to the right and the perspective changed and it was back to being 'only' a Falcon of some sort. I knew that it wasn't Concorde, but it damned well looked like it. Perhaps an even more fleeting glimpse might have convinced someone that those Frenchies had whipped their stored one out for a suprise return
SHJ