I know there’s a target in the first room, in the middle of the claw that’s hanging from the ceiling.
Another valuable target is in the second or third room on your right, where Zurg is sitting in some sort of control center - one of the targets on the outside, middle, bottom of the structure is worth something like 100K points.
In the first room, concentrate your fire power on the large red robot on the left side. The left, or second hand, of the robot will give you 100,000 points per hit. Once you have hit the robot’s target as many times as possible, spin your ride vehicle around to aim at the claw located near the ceiling on the right side of the track. The claw is easier to hit if you are past it and on the way into the second room. The combination of points from the robot and claw could put you at least halfway to the 999,999 mark before you leave the first room.
The second room is the largest and is full of targets. The volcano located on the back wall on the right side has two different targets on it. Aim for the highest “Z” to get 50,000 points per hit. Rack up as many points as you can by repeatedly hitting the volcano in this room. Once past the volcano, shoot at the targets on the right side of the vehicle they have a larger payout
Your next room will feature Zurg on the right side. Pay close attention to the “Z” target on the bottom of his spaceship. It is worth 100,000 points per hit.