Re: Diet Coke Mentos = Rocket
My only quibble here (besides the copyright issue) is that it's obvious stock vectors and images were used, and that they weren't cut out properly. You can still see some of the white background in the Coke bottles and the flames.
Otherwise I agree with the poster who said you might want to change the brand names to avoid getting rejected, and consider getting rid of the texture on the Mentos package since you did the same on the bottles.
