Rumor going around is that the third installment of the movie will be called: MORTAL KOMBAT DOMINATION. Just a reminder that I said "RUMOR"!
So far the plot will probably resolve around the Mortal Kombat Deadly Alliance video game, and maybe touch up a little on the MK4 video game.
There have only been three rumored signees to act for MK3 the movie. The first is Linden Ashby who played Johnny Cage from the first movie, this is a step in the right direction considering he is a good actor. MK3 The Movie also signed Talisa Soto who played Kitana, and they signed Chris Cassamassa who played Scorpion from the previous two movies. He will probably play the role of some of the ninjas. If Robin Shou is still set on acting, his character Liu Kang will probably die off right away in the beginning of the movie considering that is what happens in the MK5 video game. Also he signed a three movie deal, but New Line Cinema gave all Mortal Kombat rights up to Threshold, so now the movie might be a little different with special effect, ect... Plus, since the rights were exchanged Robin Shou's contract might be void or what not. I am not sure if the above is true, but I do believe I got these facts from the Official Mortal Kombat Website in the Interview Archive.