I don't have the HK version, so I don't know the contents of that disc. As far as the R1 version goes, the movie can be played in Cantonese, English, French or with the commentary featuring Stephen Chow, et al.
Here's a list of the extras:
The Making of Kung-Fu Hustle
Hosted by Chi Chung Lam (the fat guy, Weight Vest in Shaolin Soccer) and Kwok Kuen Chan (Brother Sum, Empty Hand in Shaolin Soccer), this mini-documentary shows a behind-the-scenes look at the film. The duo also show you how to wash off the old-fashioned hair gel everyone wore in the movie.
Deleted Scenes
The original cuts of the Pig Sty Alley meeting and Sing's induction to the Axe Gang.
Outtakes & Bloopers
Not as funny as the ones in Shaolin Soccer, though.
Trailers
More reasons to hate Americanized film trailers, especially with the overuse of "Ballroom Blitz."
Interview with Stephen Chow
A US exclusive featuring martial arts journalist Ric Meyers.
Poster Gallery
Unfortunately, this doesn't include the original HK posters.