Castle of Illusion

When you finish a level, when the end-of-level screen (where your bonus points are added up) appears, press Start rapidly until you hear a ringing sound. You now have one more life than before.

At the end of the second level in Toyland, you'll come across a bag of marbles. If you pick the bag up and proceed to the right far enough, when you go back to the left, the bag will reappear. Each time you pick the bag up, you'll receive 1,000 points and extra marbles (up to 30.)

As long as you are on the vines in the second part of level 1-1, you're invincible. Swing on the vine and get all the points you want and up to ten men. You'll average about 95,000 points an hour.

There are several hidden passageways in this game. Here are a few to get you started.

Level 1-1: To find Level One's secret passage jump down from the second angled ledge and go underground. The first passageway to the left has a false wall which Mickey can pass through. At the end of the passageway there's a variety of bonus goodies.
Level 1-2: Go to the cliff by the forth rope and drop off the left side while holding to the right and you'll get ten apples!
Level 1-4: Jump into the hole by the fifth tree and walk to the left through the rocks to find a room with a free mouse and two stars.
Level 3-1: There's an identical secret passageway, just before you go underground. Proceed just as in Level 1-1 and you'll find another false wall and goody room.
Level 4-3: When you find a tea cup, jump in for a swim and you'll find all types of power-ups. Be careful of the sugar cubes!