I barely remember anything from this movie, there are two scenes stuck in my head. I think it is from the late 80’s or early 90’s but could be wrong, i was very young when i saw it.

Two scenes i remember:

There is a group (or two?) looking for something, and they have a large crystal which is placed in a hole in the side of a cliff, it falls down and triggers some machine which opens a huge door in the side of the mountain. I remember one person not wanting to put the crystal in the hole and saying something like,”It could fall all the way to hell for all you know”

In the second scene i remember one group of people cross an underground chasm with a flying carpet they filled with natural occurring helium or something.

I may be off on the details, the memories are very fuzzy, I appreaciate any help