References (not all of which are real):
Greenland and Nunavut (Canada) have a disputed island called Hans Island
Guyana, Suriname (Dutch Guyana) and French Guyana are all Guyanas
The Mexican state of Chiapas once tried to break away, and the state borders Guatemala
Argentina has a generic "we will invade our rival" joke
Nicaragua is one piece because its proposed canal was never built
Tobago is part of Trinidad and Tobago
Guam made it out in one piece because the USA got rid of North Korea
Germany regained its 1871 land apparently
Macedon was an empire which took over Greece, then the entire Persian Empire
Bulgaria used to own a chunk of the Balkans
There are many Hungarian speaking communities left outside of Hungary, and another Hungarian speaking "island" in Romania
Belgium, Netherlands and Luxembourg all make up a group called BeNeLux
Portuguese Empire
England used to own Wales
Afghanistan never had a single government in de jure and de facto status, but it does in this video
Bangladesh was once part of British Raj
There is a region of China called Inner Mongolia, which is more related to Mongolia than the Han Chinese area
New Guinea is an island north of Australia, Papua New Guinea occupies the eastern half
The East African Federation is a proposed country uniting Uganda, Burundi, Tanzania, Kenya, Rwanda and Sudan.
Angola has a province called Cabinda separated from the rest of Angola by DRC's tiny coast
Gambia only borders Senegal
Guinea and Guinea-Bassal have similar names
Algeria's capitol is Algeirs
Ghana and Togo border each other
Niger and Nigeria have similar names as well
Egypt has de facto control over a region called the Hala'ib triangle, a disputed land with Sudan
Gabon also has a territorial dispute with Equatorial Guinea
Republic of Congo and DRC have similar names
Lemuria is a mythical continent in the Indian ocean, originally thought of to explain similar plants on Madagascar and Australia
Cayman is not Gay man
Hong Kong took over China
Yugoslavia is back