Steve,

Yes, it is a GPS track that my husband and I took in June 2012 when we were hiking down to Lone Pine from the PCT. Same with the photos -- all taken in June 2012 on the way down the trail and on the way back up to the PCT. And as you mentioned, Google Maps misidentify the trail, but our track is correct.

As far as the maps, the app downloads topo maps of the Landscape style (http://www.thunderforest.com/landscape/), which are in turn based upon OpenCycleMaps. You can use those when you don't have cell phone service. When you do have service, Google Maps load in the background.

Alice