hmmm
I think its somekind of collecting all trick you see around and second ... I think the just activated spectator mode and fly around till they found this or that shortcut .... or just look at the thing from above
remember how old this game is every single shortcut could be found by accident and all together you have this ...
there is also some weird thingy I found ...
where the rocked starts ... there is a wall 2 pipes are going up and if you walk next the pipes up you will get very very slowly higher and higher till you are out of the scene ... and this looks like backstage