Chung-Li Cameo:

Go to a house in Bleak. Talk to the kid, and then answer yes when he tells you to put 100GP on the table. Then, when he asks you to turn around, choose no twice, then the third time ,say yes. After that, you will see Chung-Li.

9999 Experience and 9999 Gold:

Before battling Jade in Obelisk, he will ask you if you want to join him.
Answer "Yes", and whenever he asks you if you want to change your mind, answer
"No". Do not push any buttons and he will soon say, "I'm bored. Entertain me!".
After this, there will be a battle scene. You will fight a D.Flea, a Crab, a
Flower, a G.Slime, and finally an M.Slime. The M.Slime will give you 9999 Gold
and Experience. You can easily repeat this process as many times as you wish.

Getting the Rod5:

With the sphere, you can also reach Tunlna. Fall down a pit to the left of the Vault in the princess's house, then search the box to find the Rod5. This is helpful at fishing wells.
How to Change any Box/Crate/Barrel You Push Around Intangible:
First off, find something you can push. Now get in front of the object. Push forward on the object and EXACTLY before you begin to move, hold another direction. If you have done this right, you will slowly move the different direction and the object will not move. Although the object is still visible, it is now actually intangible and you can move through it and around it (sometimes it shows the object following you, but it still becomes invisible).