Revealing mistake: If you watch the deleted scene "Chaucer's speech" on the DVD you can see that when William is in the stocks, Chaucer makes a nice speech about him and the crowd starts chanting "William, William...". Well in the movie it is made to look like they are angry with him but if you watch their mouths, they are mouthing the name William, but all you hear is yelling. (01:52:00)
Continuity mistake: In the Paris tournament, when William stops losing and starts winning, the 3rd knight he faces (the one whose helmet he knocks off) sets off with his lance in his left hand, but it switches to his right. Also, in the shot from behind the opponent, William moves his lance away from his adversary as they ride by. (01:22:25)
Continuity mistake: In the scene where everyone is trying to convince William to run away before he is arrested, Jocelyn starts to cry. At one point, the tear river runs down the middle of her cheek, and in another shot (toward the end of the scene), it runs over by her nose, and then it's back in the middle again. (01:46:35)
Continuity mistake: Right before Wat Falhurst gives Sir Ulrich the kiss from Jocelyn there is a horse behind Wat that is being tended to by three guys. Each time the camera pans back to Wat from Sir Ulrich the horse is either there, gone, or moved to a different location. (01:14:30)
Continuity mistake: In the scene where Ademar is in France with the Free Companies, it is raining fairly heavily at the beginning of the scene. In the following shots, showing just Ademar and his squire, there is no rain visible, just fog in the background. After Ademar stabs the knife through the tournament result sheets, there is another wide shot, with rain again visible. (01:09:10)
Continuity mistake: When Sir Ulrich first battles Count Adhemar after the first hit Sir Ulrich is taking to Roland stating how hard he hits. The camera angle from the front shows his arm bent in front of him but the camera angle from the back shows his arm resting on his leg. Happens about 3 times during the entire scene. (00:45:40)
Continuity mistake: As the scene in which William is knighted begins, Roland takes a position to his right, holding a staff in both hands, raised to his right. Once the Prince reveals himself and approaches, Roland has the staff touching the ground, which is fine, he may have done that as a response to the Prince. Cut to a close-up of Roland's face an instant later, now he looks worried and the staff is raised to his right. Cut back to the Prince an instant later, and the staff is back on the ground.
Continuity mistake: In the scene where Ulrich first rides to compete as Sir Ector ("We Will Rock You" is playing), there are various shots of the crowd enjoying the song. The woman seated to the right of the tournament sponsor (as you look at the screen) has a Princess Leia-type hairdo. Her buns sit high on the sides of her head in one shot, down lower in the next shot of her, and back up high in a third. (00:03:55)
Continuity mistake: When William is riding through the streets of London, Roland is shown walking in front of him. Next it shows Wat, Chaucer, and Kate walking behind him closest to the wall on the left. The next shot shows people on their left. Then it switches back and forth a few times. (01:34:05)
Continuity mistake: When Wat Falhurst is stretching out Sir Ulrich's arm after losing on purpose, every time the camera pans back to Wat from Sir Ulrich, the horse behind Wat which is covered by a striped blanket is either there, gone, or moved to a different position. (01:24:00)
Revealing mistake: At the very very end of the movie when everything has faded away and the camera pans in a circle around William and Jocelyn as they kiss, you can see a zipper in the back of Jocelyn's dress. (02:07:30)
Factual error: Worth mentioning, because we see it written on screen: in French, Jocelyn is a man's name -- even its pronounciation is different. For it to be a woman's name, it has to be spelled Jocelyne.
Continuity mistake: When William is let out of the stocks you see him take his hands out of the holes, however in the next shot you see him take his hands out of the holes again. (01:53:30)
Continuity mistake: When Geoffrey Chaucer is first seen walking naked down the road, the dirt smears on his body change with every shot of him. (00:14:50)
Continuity mistake: In the scene where William is having a discussion with Jocelyn in the stables, look at the top left corner of his breastplate. Between shots it changes from being tucked under his shoulderplate to being on top of it.
Revealing mistake: In the joust montage sequence when William allows himself to lose repeatedly in order to prove his love: Just after the shot of the white flags going up, we see "William" get hit again but it reveals itself to be a mechanical double first in the way it folds over backwards in a sharp 90 degree angle (no human can bend that way), and it reveals that there isn't a person within because it breaks with the lower portion of the "body". Shot from another angle (the right) the front portion of the saddle blocks this from view.
Continuity mistake: During the last match between William and Rufus the sun changes between shots.
Continuity mistake: In the part before the world championship, when everyone is trying to convince William to run away to avoid capture, the front edge of the large shoulder plate of his armor is in front of his breastplate in some scenes, and behind it in others. He stands virtually still during the scene, except for turning slightly. (01:44:20)
Factual error: Ulrich's armor repair is either gas welded or arc-welded, not Forge welded. Forge welding is the only type of welding available at the time and is usually extremely different if even noticeable. (00:35:10)
Continuity mistake: At the end of the film, when Heath Ledger has defeated Rufus Sewell, the amount of wood pieces in the air changes between shots.
Answer: The reason he is so agitated has to do with the manner in which he won the tournament. If you'll recall, William states, "I'll not be champion until I beat Adamar." Adamar had forefeited beforehand, (not wanting to joust against royalty) therefore not giving William a true victory. After his half won victory, Jocelyn's (Shannon Sossamon's character) inane chatter just rubbed him the wrong way. It had nothing to do with what she was saying...if anyone had spoken to him he would have reacted in the same way.