Hitting flying saucer in Frame 3 determines the point value of the rest of the Monsters of that flame.
TIPS AND TRICKS
In Frame 3, if you hit the first 10 monsters in succession, a flying saucer appears. Shoot the saucer. Whatever number appears when you hit it will be the point value of the rest of the monsters in the frame.
In Frame 4, be sure you shoot the first monster that appears. An accurate shot will allow you to proceed to Frame 5 & 6. If you miss the first monster but hit the second you can only proceed to Frame 5.