There was a surprising amount of set dressing done. Some people have pointed out before that they must have put down fake tiles as the direction of the tiles in the film are diagonal (I think) instead of checkered. But as other people have said, Sydney was very run down in the 90s and many buildings were genuinely just like that. It's come a long way.

I was there two years after it was filmed. It was not that run down, not by a long shot :) And I lived in a pretty bad area (I used to leave my car unlocked because the heroine junkies would smash the window to have somewhere to sit while shooting up). I guess some of the cleanup was for the benefit of the olympics but that doesn't apply to the back street stuff.

There's roos (or at least Wallabies) that graze on a big golf course on the other side of Sydney Harbour. They've been known to make it onto the highway and cross the bridge into the city - just near where the red dress scene was filmed.

The Wachowskis have said they chose Sydney specifically because it reminded them of Chicago, which is where they wanted to film. That said I think it surprised everyone in Sydney how it ended up looking on film.

There was a film studio out at White Bay they filmed some of the movie at too which was demolished shortly after which likely explains the general location.

The movie certainly benefitted from filming in Sydney right before all the urban renewal kicked off. Doubt you'd be able to commander a train and a disused platform space today on their budget.