Continuity mistake: As Orlando Bloom is talking to his bald comrade walking through lined up guards, after they realise the enemy has arrived, neither is wearing armour. As they stroll through the arch, you see that both are now wearing armour. (02:18:05)
Continuity mistake: Just before the end of the movie in a scene where Balian and Sibylla ride on horses, they briefly stop next to a concrete cross and we can see village/houses in the far background (middle of the screen). In the next scene we can see all these houses being removed/replaced with woods. (03:00:10)
Continuity mistake: When Balian is talking with Tiberius after denying the King's proposal, watch Balian's clothing. His chain mail is visible on both sides of his shoulders in one shot; we cut to Tiberius for one line (I believe it was, "Jerusalem has no need for a perfect knight") and when we cut back to Balian, his cloak is now covering the chain mail completely.
Continuity mistake: Right before the scene where the camp is attacked, the snow on Balian's head changes.
Continuity mistake: When Balian is considering killing the Muslim servant after killing his "master", his sword is placed straight into the ground. In the next shot showing the Muslim's face, the hole is considerably bigger.
Continuity mistake: In the scenes before the battle at Kerak, the skies shift from totally clear to quite cloudy and back again in the various shots.
Continuity mistake: At the end of the film when the king of England rides away from the camp, Balian's hair changes from before.
Continuity mistake: At the battle of Jerusalem, the Muslims walk past 2 piles of rocks painted white, but both piles are the same pile - shot reused. Another reused shot was the firing of harpoon arrows with ropes attached, into the siege towers, all harpoons are the same harpoon.
Chosen answer: As Sereenie said in the corrections, Balian has spent months travelling with his father, during which time he has learned many things, including sword-fighting, and how to read and write.
STP ★