A few months ago (sorry didn't say anything about this sooner) I was on a Non-OA alt playing on the game and found out about this. Here is how a user can upload an impossible level without OA. The player may draw a track. All they have to do is collect the goal. They then press publish and press the 'X' (close button) on that window. They can then add other lines to make the track impossible, and because their player has changed the variable to say it completed the level, it can upload it. Just a little bug I thought I would report.