I've heard that too but take it with a pinch of salt.
The bombing run on the dams was performed by single planes, with one attack starting after another.
The operation was finely worked out with the bombs released at a precise altitude and distance from the target, leaving no margin for either error or daring do.
I can't remember exactly how the attacks took place in SW, but they struck me as far more chaotic and gung ho.
I think the film was made with an emphasis on technical accuracy. The cool of the aircrews was amazing, they hardly reacted to seeing their comrades going down in flames. I don't know if that's how it happened but it made sense with the general tough, stiff upper lip ethos shown throughout the film.