Pretty cool, love that it keeps track of your score at the bottom. One comment is that the user feedback when answering incorrectly displays the name of the correct country, not the incorrectly guessed country.
Example:
Flag is Brazil. Finland is guessed by user. Message to user: "You guessed Brazil incorrectly".
Example: Flag is Brazil. Finland is guessed by user. Message to user: "You guessed Brazil incorrectly".