Alright, as we have seen...
The alternate costume for Darrius is very much inspired by Jim Kelly who was in Enter the Dragon and Black Belt Jones
The Shujinko character costumes look to have the following the inspirations:
The White Eyebrown Priest who pervades a lot of the 70s kung fu cinema (such as Executioners from Shaolin, Fist of the White Lotus) and obviously made famous in the contemporary movie "Kill Bill 2" as Pai Mei
Shujinkos alt outfit looks (as another MKO forum member already pointed out) as the old master from the 70s flick "Master of the Flying Guillotine"
Raiden obviously makes references to the character from Big Trouble in Little China as well as some older 70s HK movies that use the same outfits.
Sindel even resembles the main character Yi-Hang in "The Bride With White Hair"
So... post any other references you see in the character or costume design and make sure you reference the specific movie!