In Central NJ, near Princeton, there are lots of non-existent town names on road signs - towns that used to be independent but which got absorbed by larger townships. One near us was Marshall’s Corner, named for the guy who actually discovered gold at Sutter’s Mill.
Never seen them on weather maps, though.
The various online map services try to knit together various databases, including (for the US) something called GNIS, which is populated with every possible placename USGS or hired contractors could find, and doesn’t distinguish archaic or historic placenames. I’ve discussed this with folks at USGS, and their opinion is that placenames don’t disappear, and that the mapping services are using the database in a way never envisioned. GNIS was thought of as a way to go from placename to map location, not the other way around.
Copyright traps have had no legal basis since 1991, and are seldom the reason for an error on a map. It’s just a big complicated world, and there’s virtually no reward for extremely high accuracy in mapmaking. Some of us mapmakers take great pride in our work, but no one ever returned a map to the gas station because it was inaccurate.