The ratio is 3:2, but the correct ratio is 11:7. The colors are wrong, both the gradients and flat versions. The correct RGB colors are well defined. [1]
[1] Colors and ratio are defined on this page http://valitsus.ee/et/riigikantselei/riigi-ja-omavalitsuste-...
If we did exact aspect ratios for every flag they would all be different and look shit. We tried to be as exact as possible with colors and shapes, if they don't work for you guys or are not close enough then you don't need to use them.
Not aimed directly at you, just at anyone who doesn't find them precise enough.
It's not a big problem in my opinion - no-one should be overly hung up about minor anomalies like that for web icons - but it's not true to say the colours are exact.
And to your point about correctness: there are specific issues such as illegible text in the Saudi flag and general issues such as the use or gradients or borders throughout.
Even more importantly, never use a flag to represent a language choice.
(* most major websites do avoid using flags, but one notable exception is Apple, which completely corrupts every single flag with their own shiny style: http://www.apple.com/choose-your-country/ ...)