Google showing places I haven't been

No. Your location history is never completely exact. It is because GPS location is often bad, particularly in these cases:

• If you are inside reinforced concrete buildings or trains. It is because the metal in wall (of the building) or the case of the train shadows the signal of the GPS satellites.
• If there is no GPS signal, google maps tries to use the MAC address of the available Wifi APs what your mobile can see - and compare it to the GPS signal of other google users, whose GPS at that position worked. It works in many cases, sometimes it does not (for example, the Wifi AP is actually another telephone of another Google Maps user who shares its mobile network with it).

If you see your position history (timeline) on the google, it shows you all the cities what the google thinks, you visited.

If the Wifi-based localization worked 10000 times in your life correctly, and 3 times badly, then you will see 3 cities where you never were. It does not matter that it worked correctly 9997 times, the first what you will think that you were never in Zürich or Philadelphia.

Your position timeline overweights the mistakes of the google localization. You can see these false points, many of them are airports or train stations.

Probably there are some option to change your google maps timeline retroactively.