The student follows the directions but the landmark mentioned (e.g., "the coffee shop on the corner") isn't there anymore. The student must stop someone else and ask again.
Partway through, the original route is blocked, and the local has to give a new, alternate route on the spot.
The local gives directions that are too vague ("it's over that way somewhere"), and the student must ask follow-up questions to get something usable.
The local misunderstands and starts giving directions to the wrong place; the student must notice, clarify, and correct them.