ANS:
Romania, a country in eastern Europe, has a blue, yellow, and red tricolor flag.
As does Chad, a country in central Africa (the flags of Chad and Romania are very similar).
The Åland Islands, an autonomous region of Finland, also has a red, blue, and yellow flag in a Nordic cross.
The Democratic Republic of the Congo also has a blue, yellow, and red flag.
Andorra has a blue, yellow, and red flag, similar to Romania’s except they have a coat of arms on it.
Colombia has a horizontal blue, yellow, and red tricolor flag (if you don’t count the stars).
Mongolia has a blue, yellow, and red flag.
That’s all that I can find, though I might have missed some as there are 195 countries, which is a lot.