Glitch: Invincibility
Begin game play on level 2 and find the box that can be destroyed up and far to the left from your starting location. Slowly move left until only the small shining portion of the box is visible on the edge of the screen. Shoot an arrow to destroy the box while no enemies are on the screen. When it hits, keep walking left and you should see the smoke from the explosion following you. You will not be invincible until another similar box is destroyed.