I have read this, but don't know if it's true or not

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There is a hidden Mickey as you come through a round door and spin completely around. If you can hit the hidden Mickey (which is hard) you get a million points.
Also, these do work -I posted this before but maybe it will help

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Don't forget these tips so you can blow your kids scores away!
When you pass the robot on your left (the Rock'em Sock'em type Robot), spin your car around and try to hit the Z on the *back* of the robot's left wrist -- that's 100,000 points.
As you leave the first shooting area, there is a "Z" target on the ceiling above you. If you hit the target directly in the center with the laser, you get 100,000 points per hit.
There is also a hidden target on the wall in the room that shows you the wall video of the flying Zurg ship. You can only see it for a split second while the Zurg ship is stopped and just before it gets destroyed. This is the most challenging one to find and hitting the target(Not Enclosed in a "Z") also gives high bonus points.
The top of the volcano is worth 100,000 points and it will erupt when you hit it.
In the battery room, try to hit the batteries on the bottom -- they'll fall over when you do, and some are worth 50,000 points. Also aim for the tiny batteries -- the smaller they are, the more points they're worth.
Also, after the robot, on your left there will be some creatures on the wall -- the spider is worth 50,000 points.
If you hit the moving wormlike creature that sways left to right that's on your right in the next room, it's worth at least 50,000 points.
It turns out if you hold the trigger of your laser down, you'll occasionally get 1,000 points even if you don't hit anything. When you're going through the red spiral light room, hold your thumb down for a few extra points.
In the room after that, the one with the animated rockets, follow the spaceships until they pause and aim for the Z on them -- if you look closely, you'll see a metal plate on the wall (there's one on each side) under the animation. Hitting those scores 100,000 points, too.