About the perspective issue, google 'perspective drawing' and you should find dozens of tutorials that will help you out with that. There are actual methods to getting the perspective of shapes and buildings down perfectly. Once I read two to three good tutorials about it all my backgrounds I draw now for my projects are perfect.
Aside from that, you could also improve on your facial animation. At the scene where the detectives are talking to one another, their eyes and face were pretty static, and when you had one of them moving their eyebrows, it looked like he was twitching. Just spend more time making their eyebrows move more dynamicaly and make them blink their eyes, cause I swore they didn't blink once. Anyways, good job! I like the artwork and the fighting scenes where great!