In the level "On Track", you will pass a place where it has wooden boxes hanging from the ceiling. In the backround you will hear a siren. That means that the U.S. planes are bombing the place.In the place with the boxes hanging, a bomb will destroy the ceiling.The ceiling will be all mest up.In some parts, you can see the sky from the damaged ceiling. Shoot at the sky and it will be like you are shooting at glass. Glass particles will come off too.I know it's kind of stupid, but it works!