I just encountered a stupid error in the J2O reviewing system. You can review on levels that aren't posted yet, or levels that have been deleted.

...Okay, I'll explain. Every download has a nuber: when you replace that number in the address bar with a number of a deleted download or with a very high number (like 5000, there are only 2050 uploads yet) you first get a few lines of SQL error messages and then you're transported to an "empty" download page. But you can review (and rate) there, and when you click submit your review (and the rating!) is actually added. This way I rated a not-yet-uploaded-number 10 (just to test). I recommend the admins to fix it; people might abuse this :P