Every once in a while, you’ll be able to snag a bonus after destroying 
an enemy ship. Bonuses are usually extra money or missiles but you can 
also get special shields that make you invincible for a short time or 
repair bonuses to your shields. The key is to snag the bonus without 
getting hit by enemy fire. The best way to do that is bide your time… 
you’ll have a little bit of time to snag the bonuses so wait until it 
gets a little closer and then zoom in, grab it and zoom back out.