Those are the assembly series figures, I see. I made some of them, but found them to be difficult to pose realistically. Especially tough was getting the hands to look natural holding weapons or items. You have done quite a nice job with them.
I like your diorama. Further I would disagree with the reference to the "big mistake". It may not be the best model out there but you have done it justice. I would only add one suggestion and that would be to consider depressing or setting vehicles into the scene. The vehicle looks as if it is riding on top of the surface when in fact the weight would have balanced it a bit more. Not sure if that makes any sense.