When you reach the map boundary and Pirizuka becomes "lost", if you switch to the aiming (first person) mode you can explore areas where you normally cannot go to, because the floating camera stops following you. With some skills you can explore with flying engines as well. I think it is a bug. Found in update 26.
How the fuck is this possible? We don't have Cyecos anymore dude... But if you're talking about the sky border, I guess it's true...