The worst is clearly Georgia, as Ton de Vid mentioned. Just look at zoomed-out map and you'll see that according to PI Georgia was one of the biggest countries of the world...
Just everything about Georgia in EU3-DW is bad:
- "Georgia" province does not have anything in common with any real Georgian-culture lands - it's a part of so-called Circassia and by 1399 it was controlled by GH. The same with "Alania",
- In-game "Georgia" and "Alania" (Georgian culture) are lands, which IRL never had Georgian culture as a dominant one or even one of somehow important,
- "Abkhazia" is huge beyond any sense, taking up whole north-eastern shore of Black Sea,
- "Imeretia" and "Kartli" are like one "slot" to the west too far (Imeretia is where IRL are Guria, Megrelia and Adjaria, Kartli is where IRL is Imeretia ect.),
- Half of Georgia in EU3-DW lies
north of Caucasus range, which is an absurd. Even at the peak of its power (13th century), Georgia did not control these lands, but was expanding to the south. No to say that it didn't went north of Caucasus any time from 1399 to today.
Shortly speaking, real Georgia was and is 2 times smaller and lies in a completely different place (south of main Caucasus range)... After seeing such things with Georgia and many countries in Europe, I would be afraid to even try to check countries i.e. in Asia, which I'm not so familiar with. I suspect there are gazillion of similar mistakes.