I had a weird problem in the endgame. When I got to choose if I'd stay and defend Amaranthine or go to the Vigil and defend that instead, I chose to remain in the city. After the battle there, my codex updated all the codex entries for the characters I left at the keep, and it said that they had all died honorably while defending the keep. Also on the world map, it said that the keep had been destroyed by darkspawn.
Very well, I thought, **** happens. Nothing strange with that so far (except perhaps that I actually had gotten all the upgrades for the keep).
BUT then after the final battle, in the "epilogue" texts, suddenly the keep had repelled the darkspawn, and not at all fallen or been destroyed!!

All those companions that, according to my codex, was dead, was not dead any longer in the epilogue. Every single one of them survived according to those texts!!
I believe that's a pretty big mistake (and a FAT immersion breaker!!).