Adult "Where's Waldo" Game

I found this on plime.com - a lot o’ fun!

http://www.alanoutten.com/pixelstudents.html

Is it a bit buggy? After about level 6 or so, it went back to level 1, except at the difficulty of around 7. Beating that kept me at level 1. Also, I deliberately let the clock run out but nothing happened. I was still able to pass the level.