Were they surprised?
I mean, if they made their little brother disappear, sure, but did they get in trouble? If so, I think some of the blame needs to go to the parents. What were they doing with a stand-alone closet in the middle of the room in the first place? That doesn't make any sense.
But magic itself doesn't make sense. That's the whole point.
You get on a plane, for instance, and it takes off. It doesn't flaps its wings or anything but the next thing you know you're arriving at your destination. Boom. Magic.
I guess in a roundabout way that explains why magicians pull rabbits out of their hats and not bags of potting soil.
I wonder what happened the first time somebody said abracadabra . . . eh.