Continuity mistake: After Flash fixes the timeline, he is back in Bruce's Batcave and gives Bruce a letter from his father. Bruce is working at a station and his utility belt is there as he is working on it. When the camera pulls back before Flash runs off, his utility belt vanishes. (01:17:00)
Revealing mistake: During the flashback when we see Bruce Wayne murdered, Thomas Wayne is beating up Joe Chill while in the background, Martha can be seen cradling Bruce's dead body. As she picks him up though, the animators forgot to remove the still frame so it appears as if there are two corpses.
Chosen answer: Despite the ending in Flashpoint to indicate a Darkseid invasion, War is not a sequel. It's a reboot. While both films were part of the DC Universe Animated Original Movies series, War is the first movie of the series that is now part of the DC Animated Movie Universe. This is also why the voice actors are different.
Bishop73