Power-up : After the middle of each stage there's a helicopter (a plane on 1st stage) that drops a power-up item. So, don't destroy it until it releases the power-up. Be careful with the helicopter scrap after destroying it, it can kill you.
1up player : At the 2nd and 4th stage there is a chance to pick up a 1up item: a group of blocks appears floating on the upper part of the screen, you have to shoot the blue one. You have to hit it with one shot, if you don't, the blue block will turn to red.
Moai Statues : be careful with the Moai Statues at the 6th stage (last stage). Always check if its eyes turn red, if it starts flashing it will shoot.