It sounds like a silly thing when there's undoubtedly lots more things that need to be improved and addressed (though I really enjoyed MK21), but I REALLY REALLY hope we get some proper exotic on-location settings in the next film. MK21 felt so urban and bland, only the scenes set in Japan felt even remotely exotic and visually striking. All the scenes set in Chicago, the farm, the wastelands of Outworld, the desert of Earthrealm and Raiden's cave were all so dull looking.
If you're not making a movie of MK3, I never want to see the Mortal Kombat universe look so boring (and considering MK3 always reminded me of the horror of Doom 2 Hell on Earth, there's no excuse for that either). The fact they actually deleted the scene in Raiden's bamboo garden is a crime (well none of the deleted scenes should have been deleted, considering the movie's so short) since it actually gave the film such much needed natural beauty, rich colour and Asian mysticism.
I want to see locations on par with some of the gorgeous settings seen in MK95; the real temples, ancient statues, mountainous island plateaus, the dragon boats on the ocean, the beaches, the palm trees etc. Granted it was pretending to all be somewhere in China when it was clearly Thailand (including the monks), so I'd prefer something that actually looked like the Hong Kong cinema of MK1, but I just want to feel like I'm stepping into an Asian myth when I see that dragon logo on screen, not a Hollywood action movie filmed in downtown Australia.
Even Conquest and Legacy made more efforts to look exotic than MK21 ever did.