Scene: In the hotel, during a fight scene, Korben jumps on a plank and causes a Mangalore to fly up and punch its head through the ceiling, creating a hole in the plaster.

Right after the Mangalore gets its head pushed back down and it falls, Ruby is looking down through the hole. You can see the hole is perfectly circular and the edge is made of metal, like a sewer hole, as if it were pre-made.