I saw your hint, saying that there's only 3 African countries with McDonalds, first ones i guessed were Egypt, Algeria, and South Africa.. those three....
Some more countries that definitely have McDonald's: Romania, Slovakia, Hungary and Moldova (mcdonalds.ro, mcdonalds.sk, mcdonalds.hu, mcdonalds.md). Nice idea for a quiz though. Hope you get the mistakes out.
I normally just type "New Guinea" and "Vatican" for those countries which screwed me up a bit. I guessed I also happened to misspell "Marshall Islands" and "Ethiopia". Good quiz though.
http://mcdonalds.rs/
Maybe wikipedia is not the absolute reference, but check this at least to have a proper list...
https://en.wikipedia.org/wiki/List_of_countries_with_McDonald's_restaurants