This question already has an answer here:
According to Google location history, I was in Tokyo in February. It could be that I had so much saké I'm forgetting something important, but as far as I know I've never been to Japan.
Other questions on inaccurate location history seem mostly related to minor inaccuracies because of phone connecting to nearby WiFi points.
But what technical issue could cause the location to be off by ~6000 miles?