It looks like your watch had some trouble with the satellites, maybe because you were running beside a mountain the whole time. At Km 15, you even summited one of Rundle's peaks for a few seconds!
I had a couple of those random points on my GPS track one time in a mountain race when I was only recording my location at 60 second intervals. Your track is much wackier though!
Wow, submit that to Strava and you will have some FKTs!
Hahaha! Yes, I noticed I 'summited' something...very strange. Maybe it was at the point of bushwack, really thick vegetation and Rundle on one side.