1. Why is the background so pale and out of proportion? After all, it was possible to do better lines.
2. Sprite live in their own way : when Grunt smokes; when Grunt is holding a gun; when on the back of the Grunt the weapon moved and etc. You should work on it, it's not the case.
3. The font the most disgusting thing. It prevents you from plunging into the atmosphere events.
4. you could write your own music instead of borrowing someone else's. (but this is my personal opinion, but better write your own song )
5. Well, the last thing I COULD see is the quality of the sprites, as if taken from a search, cut out and added a belt and bandages. Didn't even add any details. (And it would be better for the car to make other headlights)

There is only one result: learn to draw and animate.