that's all supposed to be in the works on the next version. views of the comic along with the scenes. there's also going to be an extended cut of the film.
This happens all the time in DVDs. studios get a release out as soon as they can, then release a better version down the road. Check out this thread at DVDTalk.com. I often don't buy a DVD if it is going to be re-released (unless i'm happy with the current available version). in the case of Sin City, the initial release is very limited.
Upcoming Re-releases List