The Dara knot is a Celtic symbol that represents strength, wisdom, immortality, community, and spirituality. The name comes from the Irish Gaelic word doire (pronounced dear-ra), which means "oak tree", more specifically, powerful root system of an oak.
The episode was definitely not shot in the Mt Shasta area. This is Horseshoe Bay, and Vancouver British Columbia.
The episode may not have been filmed around Mt Shasta as mentioned, but the opening scene of the mountain is Shasta. But I think that's as far as it goes.