First off, congratulations on completing a whole story.
Over all:
The page set-up was very confusing. Most of the time I wanted to read them from left to right, since that was the direction that the action moved towards, which in turn made the whole story confusing. I understand if you were doing that sometimes to flow the rows together, but they were less successful. Might I suggest that next you to that, have the action be more of a diagonal than a straight horizontal line.
It got better as the pages went on, but you could use more practice of including environments to your pages to tell the reader where these character are. Don't always rely of the dialogue to do that. Readers should be able to look at the art alone and understand the jest of where the characters are and what it is that they are doing. The dialogue is there to give more depth to those places and actions.
The lettering: I'm glad to see that your balloons are wide and short. However, the letters themselves feel forced into the balloons. In your thumb-nailing stage, start figuring the size of the word balloons. That will help you learn how to have your art and dialogue work together. Also, The letters change sizes often; do not do this. It looks very amateurish and further proves that the balloons were not planned at all. The bold is fine on them, but just be sure it all stays the same size. Also, your letters look to be Comic Sans. That is a really big no-no. There are plenty of fonts to choose from. Play around with easy to read fonts that fit the art of your story.
Also, on the lettering note, be sure to proof-read or even get a friend to proof-read your pages. I noticed quite a good many grammatical and punctuation mistakes.
I've noticed that the gutter often change thickness on every page. Thinner gutters on the more action sequences make since, but on the conversation scenes it just looks very strange and distracting.
Character designs: While the clothes and hair differentiate the characters, their faces shapes are almost all completely alike. Practice with different facial shapes to separate the characters from each other. Also, work more of drawing different body types. I understand all the main playing characters were roughly around the same age, but there generally body type would be different. A good exercise it drawing the characters bald and nude and working out how each of their general shapes can read differently from each other in strict silhouette form.
I will say, that I was happy to see that your hands were quite good. Hands can be a pain for many, so it's always good to see someone who can draw good hands.
Line-waigth: I noticed it more in the first few pages than later, but keep working at varying your line weights. Varied line weight art is far stronger than dead-lined art.
Pages 1-7:
I have no idea where the characters are. Are they inside a store, a market place, outside in a city, park, etc.? The reader only learns by page 5 where the characters are because the dialogue tells them. The environments should have told them before then. The introduction feels a bit awkward because we are introduced to three characters at one time who are arguing, which leaves out really telling the reader who they are.
Page 8:
The environments here are nicer. The reader can get a sense of where the character are, though a wider shot that that shows more of the room would have been a good touch so that the reader can get an even better feel for the space as well as where exactly the characters are in relation to each other.
Page 9:
This scene feels a bit strange. While it gives (I'll call her girl with hat) some more roundness, nothing seems to come of it which makes the page unnecessary. if this issue had been brought up again later on, and helped change her or something, then it could be seen as necessary. Panel 3 is nice as it shows the characters in relation to each other, but again, the dialogue tells the readers that it is a business. Pull out establishing shots more to show the environments more fully.
Pages 10-16
On page 10, be careful when using the tones. The tone on panel 1 and panel 3 look to be the same value. That can make it look like those two character are in the same place. Also, on panel 3, the dark tone 9while I understand its supposed to show the light being off) hurts your environment establishment. The tone is so dark, that a lot of your line work gets lost.
The crack becomes a big deal in the story. The fact of it happening should be brought to the reader's attention sooner than page ten. Just a panel showing it happen would do. Sometimes visuals without words can be just as strong.
On page 11, the transition to the flash back feels a bit confusing. Play around with different visual cues. Study of other black and white artists handle flash back transitions.
Page 13, Panel 4 could be a lot stronger. It is a full body panel showing how damaged she is. Really see panels like this. She should not be standing so straight since she only has one foot. This panel should show her struggling stand, showing her determination to go on.
Page 14, When did she get outside? Also, the end of the flash back and the present is a little shaky.
The montage on pages 15 and 16 feels a bit strange. It feels unfocused.
Pages 17-22:
This is a really nice scene. I really love this whole scene.
Pages 23-37:
We're at a race track, but we never actually see the whole track. This is one of the main focuses of your story, the readers should really be able to know just what the main character has to face.
Page 23, it feels abrupt to suddenly learn that the characters have wings.
Also, it feel abrupt to learn no that the main character's 'dad' is the last human. Learning things like that, will make a reader have a lot of questions that the writer needs to answer. Also, with this being a one shot, information like that feels unnecessary. From reading the story thus far, the plot is main character wants to win the race to make her dad proud. The fact the he is the last human is just unneeded fat to the story.
The race feels long enough, and gives the character a few more hurdles to overcome and reach her goal.
However, the gear at the beginning, is never mentioned after the first scene. The race is why they need it, yet it is just forgotten. Don't forget to tie up all your loose ends by the end of the story.
Page 38:
This page is unneeded for the story. If there were a planned sequel, then it would be understandable. However, since this is a one-shot, this page hurts the plot more than helps it. It brings up more questions, and would make the reader wonder how the main character reacts to the information. Also, the goal of the plot is that the main character wants to make him proud. That being covered in the last page would be far more interesting that this.
I hope this critique helps you, and keep up the good work. You definitely did improve from the beginning to the end of the story.