Whats the name of this movie?

I watched this movie as a kid, so my memory is clouded, but I remember several scenes. One scene there was a cyclops holding a boulder up to allow his "friends" to enter some type of mountain. In the mountain the main guy made a boomerang from lava or something like that. And earlier in the movie the group of people rode unicorns and when they got to the edge of a cliff, the unicorns flew to the other side. It seemed like an older movie. Kinda mythical, a lot of action.