Pre-Release Theories
If they utilize the Prime Earth universe, the Prime Earth characters will be voiced by the game cast
It'd be a great way to juxtapose the two universes even more while paying homage to the games!- Jossed. The mainstream Superman was also voiced by Justin Hartley.
The death of Dick Grayson and how the fallout affects Damian and Batman will be changed
As to make Batman more sympathetic and not come off as badly. New characters will appear that didn't in the game and comic originally
Take your pic here: Static, Icon, Simon Baz, Jessica Cruz, Harper Row, Jon Kent, Jason of Themiscyra, Apollo, Midnighter, the Elite....they may fill in more spots on Insurgency/Regine forces, be cannon fodder, etc etc.
Harley will either be killed off or at least be arrested
Harley being so Easily Forgiven and a total Karma Houdini made absolutely zero sense in the Injustice games anyway, so this is a perfect chance to correct that mistake and make her face actual punishments for her part in the destruction of Metropolis and the deaths of Lois and her unborn child.- Or she'll try to atone more for playing a part in the death of Lois and the people of Metropolis to the point of making a Heroic Sacrifice.
- Jossed. She's still a Karma Houdini.
The film will not be set in the same continuity as the games and the comics
Given that it has Darrin'd out the voice actors of the Injustice characters and Catwoman possibly being Race Lifted to match her actress (Anika Noni Rose), the movie will take place in an Alternate Continuity that is based on the comics but diverges from it considerably such as the addition of certain characters not yet present in the original story (see above) or someone who is alive being killed off here.- Not saying you're wrong, but we have seen pictures of Catwoman and despite being voiced by an African-American, the character herself appears to still be white.
- Seemingly jossed. It appears that the animated films will be in continuity with the games despite having different voice actors.
- Not missed as it is an adaptation of the Year One comics.
- Seemingly jossed. It appears that the animated films will be in continuity with the games despite having different voice actors.
- Confirmed. It is it's own self-contained story, some key characters from the game are killed off and Superman surrenders at the end after realizing how low he's fallen.
Post-Release Theories
The film secretly sets up the third game.
Considering how much The Multiverse was already involved, it's possible that the games could come across yet another Earth, one that shows them what would happen if Superman had actually given up on the Regime.