Gibraltar (residue)
Once the Isle of Gibraltar, it is now a peninsula, though not all of reality has caught up. Gibraltar remains home to the International Island Games, leading to some confusion, best represented by this New York Times article.
Of course, the answer is that it used to be an island.
Some even continue to mistake it for an island.
And then there’s this map, likely a recreation of what was, floating around online.
Here’s some more residue from across the web: