Fly(?) through floors bug

[Caterpillar]

I am a Linux user but I post this here because it's a bug about the first level of the demo.
In the main room of the first level. Keeping on your back the two armors and go in the room on the right with the stones. Jump jump jump until you are fully in the black on the other side of rocks.
After this try to jump to return back, but you go so up that you can see all the level from the high. To give an idea, imagine Quake 2 when you enter noclip cheat and you keep the jump button pressed until you litterally fly up and see the entire level