Hmm...
Well, it is what it is, it's about war, so I'm not going to say anything about that. But IMO, Metal Slug sprites are overused, so for you next movie (if you have one), try to stay away from them, maybe get other sprites which haven't been used as much).
Second, if you were going for being realistic, which you may or may not have, try to make it more like war, because I didn't see much of anything which relates to real war, other than there are bullets and people die. People were standing on high places which would expose them to bullets, people were running in like suicide bombers. So, if you were being realistic, try to take those points into consideration.
Thirdly, try to take the reviews of other people lightly. Every time somebody insults your work, don't respond like a jackass. It won't really make you look better.
But overall, the flash was okay, it's not bad but it's not perfect. I hope to see your next movie.