Why?
It's Casillas fault it went out for a corner. Just leave the damn thing. No need to give it back to him again.
Not really, it was a piece of sporting play that took a bad bounce. The Dutch player wasn't looking to score from the throw-in, so if the Dutch tried to score from the resulting corner, it would always be a stain on any victory they may achieve. I suppose it all depends on the kind of man you are.
Should Manuel Neuer have let the linesman know that Lampard's shot crossed the line? Was that a stain on their victory?
I don't know where you draw the line. The Dutch played the ball back to Casillas, fair enough, but they should have played that corner into the box IMO.