I'm not a fan of the green, I'm not sure if it's just the wrong shade or if it should be an entire different colour, but it doesn't seem to me to fit quite right. Contrast is good, but it's just too much of a contrast, especially considering how small and insignificant the oval is compared to the logo as a whole. Maybe the shape and size could do with tweaking as well.
Other than that I think it's fine, I like the flags and the rest of the colours look great.