I'm trying to track down a movie about two kids who happen upon a leprechaun at their grandpa's farm. There's some connection with a white horse, and they cross into a magical realm through the rainbow. There is also a part where the fairies or leprechauns slide into a pit and a giant round head comes out of it and spits out gold coins. Wild I know. I think it was made in the 80's or late 70's. It could have been a TV movie and could have been produced by Disney. That's all I remember about it.

Possibly The Great Land of Small (1987) - IMDb

That's it. Thanks so much. Those vague memories have been haunting me for awhile now.

You're welcome. I actually had the same problem, vague memories of the movie but no name to go with it. I actually believe on found my answer on this website as well a few years ago. Then of course I couldn't rest until I watched it again. The movie is so obscure that it's not on DVD but I was able to track down a VHS copy on eBay or Amazon. You can probably find a website to watch it at for free. If you like strange movies from the 80's, you should check out IMDb - The Peanut Butter Solution (1985) , that's another one that bugged me for the longest time until I got the name off this website.