I really like this image just as it is! Great attention to the suit details!
But if I had to offer any advice it would be to be a little more creative with the background, it's a bit bland and light, needs to be a bit darker. It's almost as if you spent so much time on the main subjects that you just did not work out the background.
I like the way the atmo is interacting with the subjects in the midground, but it seems a bit monotone and washed out. Reminds me of smog..........which is great if that's what you were going for! LOL!
The characters are a bit cartoony, but I like them that way! You could invest a bit more time adding details to the faces to make them appear a bit more realistic ........but as I said, they're fine the way they are.
Last thing is, for future images, all but one of the heads are similarly shaped. My eye is heavily drawn to the hamerheaded character. He would have been better as the front man.
Great work!