while the humans are away.......the cats will play!

we came home this afternoon, and after being home a while, I realized the kitty tower was on its side, the way I put it when I throw the sheet over it for them to play. but I didn't put it like that! I had to think... then I remembered that I had seen them climbing it before leaving the house.
they knocked it over!! oh my God then I saw the valance above the glass door, it was all messed up! one of them tried to jump up there or maybe when they jumped back, and the tower fell! one of them could have been seriously hurt or killed, if it fell on them! they have all eaten and played and seem to be fine, but I wonder if one of them maybe could have some bleeding internally? do you think that could happen if they seem ok? or would they be acting hurt? no one is limping, they all seem fine.
damn, just what I need, like I don't have enough to worry about.

should I call the vet?

beware of any cat furniture you have, that this doesn't happen to your cats. mine are just too wild!