Advantage Ball: Carefully minded throughout. At the beginning, Adhemar has the advantage by virtue of his greater experience, but once William finds his feet and begins to feel more confident, he begins to win easily. At the end, Chaucer's Rousing Speech gives him the edge he needs.
The real Ulrich Von Lichtenstein — yes there was a real one! — was a 13th c. knight who, on one occasion in his career of errantry, rode the tournament circuit in the guise of 'Queen Venus' complete with silk gown over his armor and long braids of false hair dangled beneath his helmet. He was a huge hit and the tour a massive success with a final score of three hundred broken lances without a single fall. Somebody really did their research to unearth Ulrich. That or they read the Horrible Histories book on knights.
Word Of God states that the musical anachronism (as well as some of the dialogue "It's called a 'lance', hellooo.") was done intentionally to illustrate that people of the era thought of their music pretty much the same as modern people do of current music. No such excuse for the clothes, though; the costume designer simply though they looked neat.
The costume designer did make all the outfits from period accurate materials and using medieval techniques.
Aristocrats Are Evil: Adhemar, the evil rival, is Count of Anjou. On the other hand, the prince is a good guy, and the hero's friends are seen making up stories about how evil his aristocratic opponents are in order to encourage him to beat them. It works a little too well.
A count of Anjou is a pretty good choice for an evil aristocratic antagonist!
Audience Participation Failure: At one point during the filming, the Czech extras hired to play a crowd watching one of the tournaments (very few of whom actually understood English) were supposed to cheer wildly when Heath Ledger defeated his opponent. But, as most of them didn't understand Englsh, the crowd hadn't actually understood their instructions, and when the fight was over they stood there silently for almost a minute, staring at each other in confusion. When actor Mark Addy abruptly broke into wild cheering, the crowd finally got it and began to cheer as well. Director Brian Helgeland thought this was so funny he actually kept it in the film and reshot some sequences before and after to make their reaction more appropriate to the story.
William: Wat, you remember church as a boy. The fear, the passion. That's what she makes me feel. And for that, I say my rosary to Jocelyn and no one else.
Wat: William, that's blasphemous.
William: Then may I burn in hell.
Blatant Lies: Prince Edward justifies knighting William by announcing that he's discovered Will is descended from nobility, then basically dares anyone to call him on it: "This is my word, and as such is beyond contestation." Justified in that the Crown Prince could grant knighthood to anyone he wanted to without having to explain why they were granted knighthood.
Cerebus Callback: In the scene where William first arrives in London, he imagines that a young boy cheering him on is himself as a child. Later on as he sits in the stocks the same boy runs up to him and slaps him in the face.
The Champion: Despite being motivated to joust for a variety of personal reasons, partway through the movie Will is ready to lose every single match he competes to prove to Jocelyn he is her true champion, putting at risk all these other goals.
Chekhov's Skill: Subverted with William's swordsmanship—he's shown early on to be very good in the sword, and wins a tournament in the sport in his first go...then declares that it's Tournament Champion or nothing and he never picks another sword up for the rest of the film.
Deliberate Values Dissonance: Played straight, then subverted. William is stripped of everything, put into the pillory, and humiliated for daring to rise above being a peasant squire. Then the Prince knights him anyway.
Dirt Forcefield: Mostly averted, as characters appear just as dusty and dirty as they ought (and the Black Prince has a bad case of Helmet Hair when William reveals him), most of the time. Played straight, though, when Kate is shown working on the below mentioned Nike armor; a blacksmith working in her forge ought to be covered in soot, while she's just got a little bit of dust on her forehead.
William: I canít. Love has given me wings, so I must fly. I canít explain it. She makes me feel like a poet.
Roland: You may feel like a poet... but you sound like an idiot. You donít even know her name.
William: Her name? Her name is Aphrodite. Calypso. Venus. Take your pick.
Fake Brit: Australian Heath Ledger and American Alan Tudyk both put in pretty convincing performances.
Ledger certainly; Tudyk in some early scenes veers between pretty convincing, slightly over the top, and What The Hell Is That Accent? (Of course, given the era the film is set, none of these is any more "wrong" than the others). It's generally pretty convincing in the later scenes.
So convincing is Tudyk that he's often mistaken for being Fake American; he's from Texas!
Forging Scene: Kate notices that Will wears armor that wasn't made for him. She volunteers to make him some that's so light-weight he wouldn't know he was wearing it. After she is finished the knight is presented with a suit of shiny new armour.
Grand Romantic Gesture: Will purposefully loses a tilting match to prove his love (getting beat up in the process); to paraphrase Jocelyn, when Will tells her he'll win the tournament for her, "You would win the tournament anyway; if you want to prove your love, you will lose." Then, once he's taken his lumps, she sends her handmaiden to tell him if he loves her, he'll win the tournament. This does not go over well with William, or his friends.
Chaucer: There she is, William. The embodiment of love. Your Venus.
Historical Hero Upgrade: Edward the Black Prince is portrayed as a heroic and likeable individual who values William's courage and knights him despite his common birth. The historical Black Prince was well-known for conducting brutal scorched-earth campaigns that ravaged the French countryside, and to have despised and scorned the lower classes.
The characters do mention his pillaging and burning of villages and appear very afraid to the point of immediately submitting defeat when finding out his true identity at one of the early tournaments. Edward's fondness of William despite him being lower class is motivated by William doing him two big favours earlier in the movie when he had no reason to do so, and willingly let himself be arrested instead of fleeing. He also likely did it to spite Adhemar who if not for William, would have become the World Champion.
They surrendered rather than facing him because wounding a royal, even in a tournament, was a big mistake. This is explicitly stated in the film.
Hollywood Healing: William gets a piece of his opponent's lance stuck in his shoulder, and he cannot hold his own lance. As soon as William wins the championship, he can move his arm normally, and there's no indication of injury. And there's no mention of removing the piece of lance stuck in his shoulder, which would be very risky surgery in that age.
Informed Attractiveness: A great deal of fuss is made of Jocelyn's beauty. The other female characters are just as attractive, if not more, but their beauty is not worth mentioning by the male characters.
Kate invents the Bessemer Process for heating steel 400-500 years before it happened. William is initially ridiculed for wearing thin, light armor. At least until he nimbly leaps onto his horse.
Her etching "the mark of [her] trade" (the Nike logo) into her armour, which is also received with ridicule.
Jerkass: Adhemar, upon first meeting William, immediately insults him several times and he just gets worse from there. They seem to have even gone out of their way to make him completely utterly dislikeable.
Knighting: William's eventual reward, thanks to Prince Edward.
King Incognito: The Black Prince. Twice, if you count the crowd scene.
William: Wat, you remember church as a boy. The fear, the passion. Thatís what she makes me feel. And for that, I say my rosary to Jocelyn and no one else.
Wat: William, thatís blasphemous.
William: Then may I burn in hell.
The Lost Lenore: A rare male example of this trope being blacksmith Kate's dead husband.
Love Makes You Dumb: William fully understands this trope, as after making a faux pas to Jocelyn, she tells him that if he loves her, he'll lose. And so, at the beginning of the next tournament, after the flag for William's first tilt is dropped, and his opponent spurs on, the four members of the Five-Man Band cheering William on...
Roland: "What are you doing?"
William: (sitting on his horse, going nowhere) "...Losing."
Wat: "I don't understand."
William: "...Neither do I." CRASH!
Marquee Alter Ego: The most likely explanation for William removing his armor in the final battle is so we can see Heath Ledger's face.
Meaningful Name: William Thatcher, a Thatcher being a tradesman who makes roofs for buildings out of straw mat, in other words, most definitely not a nobleman by birth.
Motivational Lie: At one tournament, Roland tells William that his opponent is cruel to his peasants. After an irate Will has charged off to thrash the opponent, Roland remarks that it's probably true.
Nom de Guerre: Two of them, both due to the men in question trying to hide their identities for various reasons:
William Thatcher styles himself as Sir Ulrich von Liechtenstein, to hide the fact that he is a peasant.
Edward, the Black Prince, goes as Sir Thomas Colville, as nobody would dare tilt with him if they knew who he really was. Notably, Edward is entirely unsuccessful in hiding his identity as word gets around quick who he is.
Not Even Bothering with the Accent: Done deliberately — Laura Fraser was apparently expecting to be asked to put on a generic English accent, as usual, and was delighted to be allowed to use her natural (sexy) Scots accent.
Not So Different: A rare complimentary fashion, Edward laments how alike he and William are.
Edward: What a pair we make, huh? Both trying to hide who we are, both unable to do so.
The Oner: William and Jocelyn's long walk-and-talk scene in the cathedral.
Pair the Spares: Roland often becomes a Beta Couple with Jocelyn's handmaiden Christiana in fan fics. There are several scenes in the movie in which one can see Roland and Christiana chatting happily in the background. Made explicit in a deleted scene where Chaucer's wife visits the tournament. Jocelyn and William go off together, Roland and Christiana go off together, and Wat attempts to go off with Kate but she just gives him a cookie and walks in the opposite direction. He's good. Food is his first love.
Interestingly enough, William is the one who does it.
Screw the Rules, I Make Them!: Edward, the Black Prince, pulls one of these while William is in the stocks, even going so far as to personally knight William himself just to allow him to compete.
Self Proclaimed Knight: There are two. One is the classic struggling underdog, William Thatcher, the peasant who's masquerading as the knight Ulrich Von Lichtenstein, and the other is Sir Thomas Colville - otherwise known as Edward, the Black Prince, jousting in disguise.
Shaming The Mob: Subverted in the theatrical cut; Chaucer, having previously demonstrated his ability to work a crowd, tries to shame the mob that gathers around William when he's in the stocks. He gets as far as three words in before the mob silences him with a volley of rotten vegetables. However, in the extended cut of the film, Chaucer succeeds in Shaming The Mob into chastened silence before Prince Edward steps in. This scene was cut to beef up Prince Edward's role.
Sigil Spam: There's a deleted scene where the trio discuss their coat of arms and decide on three phoenixes. The phoenix can be seen emblazoned into various clothes and other items associated with them.
So Beautiful, It's a Curse: Mocked; Jocelyn, admonished for her beauty by a priest, laments it in a deadpan monotone to get him off her back.
Throw It In: Besides the aforementioned "We Will Rock You" opening, when Will wins his first sword match, the crowd is silent until Roland spurs them on to cheer. As it happens, the extras who composed the audience were Czech and didn't realize they were supposed to cheer when Chaucer finished his speech.
According to DVD commentary: Jocelyn's "Oh that is lovely!" in response to a priest's gesture prompting her to kiss his ring was an adlib. "Your entrails will become your extrails" was an audition adlib that helped Alan Tudyk get the part and made it into the film.
The knight that gets knocked off his horse in the opening scene of the film? That's Heath Ledger's stunt double, and the entire scene is actually footage of an accident he had while filming. He was genuinely knocked unconscious.
Training Montage: To the tune of "Low Rider", featuring an array of increasingly-inventive lance training set-ups, with Roland and Wat taking most of the punishment from both William's initally terrible jousting skills and his all-too-good swordsmanship.
Worthy Opponent: Sir Thomas Colville to William. Colville is actually the Black Prince, Edward, jousting in disguise much like William is, and anyone who realizes Colville's true identity instantly withdraws rather than risk hurting the Prince. William does not withdraw - much to Edward's delight.