A bit disappointing

This would be a really awesome game if it weren't for all the bugs. Like you say, the walls are a bit buggy, and also your collision physics are a bit off. This has good potential, though - if you ironed out all the bugs, this could be a riveting high-velocity racing game, like F-Zero style or something. It would be worth the effort it you could fix it up.

A Good Start

I'll start by saying that the graphics are very nice, all of the ships look decent, as well as the backgrounds. The pilots look a little strange though. Now for the critisims, the ships all look different, but the handlings seem almost identical and I could not easily tell exactly what was different about them except for their appearance and size. The race tracks were very bland and boring, granted it is a demo, but there was nothing interesting about the tracks themselves. A suggestion I might make would be to insert boosters, objects in the way, something to actually require some skill or reflex. I was pretty bored while driving the things, I'm not sure how you are imagining they are propelled, but I might suggest some kind of sound effect to go with the driving, and a glowing at the back to suggest a jet? The speed could be increased to make the game more engaging and intense as well.

)

I look forward to seeing the full version

good but glitchy

whenever you hit the wall, you get stuck, and can't get out for awhile, and this is really annoying when you're racing the comp that breaks all the rules by a)going faster than you b)just running you over and when you hit him you bounce off, and lose speed c)he cuts corners going off into the black space, completely ignoring the rule of getting your ass stuck d)he makes impossible turns taking huge angles at high speeds. You also have no time to start going before he just takes of flying.

The second course is nice, in that in is easier to avoid the walls, and what is with course 3 being under "construction?"
well, this has definite potential, but it has a lot of bugs, and i hope this helps you out.

Flawed, but not bad

I really like the idea of this and you've got most of the basics sorted, which is great. However, there are a few significant problems I've found with the game - hopefully you can improve on the following:

Selecting your character doesn't always work properly. For example, I chose the guy with the tiny red eyes and the massive black hair/helmet, but in the game it showed me as the weird red lips thing.

There is a very-easily exploitable bug in the game's code - you can simply start a course and reverse/accelerate over the blue starting line a few times to finish the race. While I don't know anything about making this kinda game in Flash, I'm assuming that when the player's vehicle makes contact with the bar the game registers this as a completed lap. Seeing as how you can simply cheat and complete a 3-lap course in about five seconds, you probably want to fix this!

Another problem with the lap system is that the course will end when you start the third lap, not when you've finished it. This again appears to be a problem caused by the starting bar - because you get placed right before it at the start of a course, you have to go through it, and this makes the game think you've completed your first lap. I'm sure there's a more solid way of fixing this, but in the mean time you could simply make the player appear in front of the bar.

Other than that, it's just minor stuff like perhaps having a few different music tracks and adding stats for the different vehicles. Still, what you've got here is pretty good and despite the obvious flaws it's actually pretty fun to play.

I really look forward to seeing the finished version of this, good luck with it!