Ok, Jaimie now help me with one of the jungle levels (PC version):
blue key / red door on one side, red key / blue door on the other side.
The only ways I could pass this level was A) chase HQ on the last key B) get a blue rainfall and get a fly helmet. Otherwise when you fall first time and get the blue key you break the floor and are not able to get back to the red door again. See of which level I'm talking about?