How can this be in anyway mistaken?
If you think that you percieve things exactly as they are seen ( sensed) , then you are wrong, and you are more susceptible to this kind of illusion than those who understand that the human brain has a particular area of weakness here
IMHO, this aberration is only bewildering because, as far as we know, both pilots were affected.
That both pilots were affected is the greatest clue that whatever programming of their expectations that had occurred prior to turning final was strong enough to influence both of their perceptions.
On a different tack, have you ever been so knackered that you slur your speech and can't construct sentences properly? I wonder if we will find out that the combination of rostered duties and the individual home lives of these two meant we had two fatigued pilots up front.
I know I'm not the only one to wonder.