Other mistake: When the guards are breaking into Cassandra's bathing room, we see a guard's arm reach through a hole in the door to unlatch it. However, you can see the door has come off the jamb, with a big gap, before he reaches down to pull the latch.
Other mistake: In the rebel village toward the end of the movie, Balthzar's scar on the left side of his face keeps changing. Sometimes the scar is barely there and others it is only partially there. (01:13:40)
Other mistake: In the scene where Mathayus happens upon the hide out of Balthazar and his people and are confronting one another, Balthazar's necklaces change from being messily arranged to neatly graduated in frame to frame. Surely he wouldn't have been rearranging the necklaces while confronting the Arcadian? (00:53:20)