Unlimited Extra Lives:
In the beginning of the game, get the extra life on top of the fountain.  Then, pause the game and
check your status.  Unpause the game and there will be another extra life on top of the fountain. 
Keep on doing this for unlimited extra lives!

Extra Life in the Park: 
In the park level, follow the road from the start.  Walk up to the second fountain you come to.  Go
left and follow the road come to until you see a statue on the right that looks like a woman holding
a long piece of paper.  Tail whip it 3 times.  Each time you hit it it should go a little off balance. 
After 3 hits, it should fall over and a life will pop out. 

Secret Level:
Go outside the museum level to the big statue. Walk behind it and it says " 02P " That means when
you get your power level at 02, push the statue and you should fall into the secret level.