One I particularly had in mind was a discussion on this forum a couple of years back about Table Mountain, close to the city of South Africa.
Another example is this one not far from Vancouver. While this might be a bit closer to “wilderness”, it seems that the hikers originally followed a reasonably easy and popular hiking trail but ended up on a highly technical trail that looked the same on their map.
Also from Vancouver, and apparently close to the northern suburbs of the city, is this incident. The fact this was blamed on Google Maps rather than OSM doesn’t affect my point about the dangers of general-purpose maps.