Really great image! I noticed how many people want to know how you did this, so maybe you should consider writing a tutorial on it?!? Very nice sequence shot and colors - I love it. As xcharrier said though, there are a couple of the subjects that look like they could be a little sharper, but that's a minor detail in the overall impression of the shot.
The editing job looks great... but a couple of the pics look like they could have been sharper... looks like a little motion blur. It looks overcast or low light so I can see why it would have been difficult to get a faster shutter. Just open up the aperture and maybe bump up the iso if need be. Great shot none the less.
That's really good. The only improvement I could suggest is if you would continued the sequence to include the ambulance arriving and carting him off:)
Great photograph. Of course, on your first image, you even get lucky enough for the biker to wreck. That is great! One question, how do you do a sequence shot like that?