[the fall guy]

Sorry for the duplicate, I just found out someone else posted the level1-trick already.

But maybe you didn't know that you can finish the game with negative time left:
If you enter the screen with Jaffar just wait left of the floor-trap and let the time expire. Jaffar obviously lacks the magic to stay there and wait for you to fight and kill the princess at the same time, and thus if you beat him after 60+ minutes the princess is still alive...

BTW, my best time is about 54 minutes left. No cheating, but a strange bug that teleported my right to the end of the final level after leaving level 1, haha!