Revealing all item locations
Go to the area in Skytown where you must get the first part of the bomb you have to make using your ship. Near the bottom is some Phazite; shoot the switch inside to activate the satellite system. Go to the top, and go around the walls using the spiderball tracks and bomb all the bomb slots to get markers on your map revealing the location of every expansion (Missile, Ship Missile, and E-Tank) in every part of the game, except the items in the Valhalla.