There's a really strange movie I remember seeing once a looooooong time ago. I pretty sure it was made for TV - I don't remember any cast member names. Here are the details I remember (and I'm not making any of these up.)

A couple of children, a brother and a sister, find this leprechaun/wizard (played by an adult little person actor). At first, they feed him. The soda makes him float to the ceiling until he belches. Then, he proves himself to the kids by granting a wish. They wish for their dog to be with them (they are away from home, I believe). Once he grants the wish, he reveals that he has lost a bag of gold dust. The gold dust is found by a man, who soon becomes obsessed with it.

For some reason, the leprechaun has to bring the kids to his home kingdom, where the king is portrayed by the same actor as the leprechaun. (presumably they are twins). There is something called "Slime ode" (sp?) and a random woman slides down a slide into this thing, and emerges in a butterfly/fairy costume complete with wings and flies away.

It's revealed that the leprechaun only has one spell left, and has to decide whether to send the kids home, or get the gold dust back.

The Great Land of Small (http://www.imdb.com/title/tt0093116/)