Lookin' good so far and as has been said earlier, there really is some nice rendering in this image - such as the ground and the rightbot's legs, however I think there are still a number of issues. I know you're nearly finished but:
I think you should consider changing that ultra-saturated burgundy colour in the UFO's explosion; it seems a bit out of place. And please, please consider St0ven's explosion edit :f Currently your UFO explosion looks more like a crazy jellybean pile than an explosion
Also, I think your explosions should act as a more prominent lightsource in this image, especially the front explosion which looks pretty intense; it definitely seems like it should have more of an effect on the nearby metallic leg.
I think the two men near the UFO's explosion should have less detail/contrast; right now you're showing quite a clear distinction between the outer part of the head cover and the actual visor. But since these guys are so far in the background I think that this kind of sharp detail would actually be more or less lost.
Your spaceships in the top left seem very front on, making them look as though they are just flat shapes glued onto the sky. Maybe add an extra colour just to give them a little bit more of a feeling of depth and perhaps tilt them a bit.
I'm not really convinced by your stars, they are very evenly spaced; I like the big stars but the smaller ones (1x1/2x2) don't really give the impression of being stars, especially the brightest 2x2 stars which kind of just look like solid squares floating in the sky.
If your front man has indeed been shot with a laser, then I think it would be more convincing if he were lying on the ground or something (?). At the moment he's all like "'Yo, sup guys. I think I accidentally spilt some stuff on my suit". One problem you have here is that he is wearing a suit and therefore you cannot see the expression in his face. If it were possible to see his expression, then it might be easier to convince the viewer that he has just been lazor'd, but unfortunately you don't have that luxury. Also, as I alluded to with my stupid hypothetical quote, his suit looks as though he has splashed some food on it rather than it coming across as being a laser wound. I am not entirely sure how this could be fixed, but maybe make the hole neater; lasers are pretty clean when they cut through things.
Also, you have a random red rectangle in the top right corner.
I look forward to seeing this submitted when it's done
PS: Finish off your bridge image next >;3