I know what the author was trying to do, but having Mina get lost seems weird given what has already been established. She knew how to get to the supermarket, so she used some kind of combination of mapping software, gps, and path-finding. She was even able to improvise when the pedestrian crossing was "broken", routing around it. So returning should have just required following the same path backwards. She didn't need landmarks when going to the store, so why did she need landmarks when going back? Even without internet access to ask google for a path, she should haven an internal map of the area she can use to route independently.
It's a cute story, but I'm annoyed by the inconsistency.