Trivia: When Gordon is promoted to Commissioner, Heath Ledger improvised the Joker joining in with the applause.
Trivia: To prepare for his role as the Joker, Heath Ledger lived alone in a hotel room for a month, formulating the character's psychology, posture and voice (the last one he found most difficult to do). He started a diary, in which he wrote the Joker's thoughts and feelings to guide himself during his performance. He was also given Alan Moore's comic "Batman: The Killing Joke" and "Arkham Asylum: A Serious House on Serious Earth" to read. Ledger also took inspiration from Alex in A Clockwork Orange (1971) and Sid Vicious.
Trivia: While in the nurse uniform, The Joker's name badge says Matilda. This is the name of Heath Ledger's daughter.
Trivia: Michael Caine had never met Heath Ledger before. He later said of the Joker's arrival at Bruce Wayne's fundraiser: "I'd never seen any of it and the elevator door opened and they came out and I forgot every bloody line. They frightened the bloody life out of me."
Trivia: This was the first film since The Lord of the Rings: The Return of the King to remain #1 at the American box office for four consecutive weeks. It was finally knocked out of the top spot by Ben Stiller's Tropic Thunder.
Trivia: Because of a ruling shortly before the Academy Awards ceremony, Heath Ledger's daughter Matilda will gain possession of his Oscar statuette on her 18th birthday in 2023.
Trivia: In the restaurant scene, right when it begins with Harvey and Rachel talking, if you look to the bottom right of the screen, Heath Ledger, who is not wearing the Joker makeup, is sitting at a table with someone. [This is up for debate, as it's a strong likeness but not definitively him. Regardless, worth a look.] (00:19:15)
Trivia: Robin Williams, Lachy Hulme, Paul Bettany, and Adrien Brody all expressed interest for the role of the Joker before Heath Ledger was cast.
Trivia: In the banquet scene, when the Joker and his troop arrive, the man that the Joker says reminds him of his father is Senator Patrick Leahy of Vermont. Senator Leahy is a huge Batman fan and has lent his voice to the animated series and also had another small cameo appearance in Batman and Robin.
Trivia: This marks the second time movie characters adapted from another source have lept off the Two-ifc, the world's third or fourth tallest building, in Hong Kong. (The similar-looking building that Batman enters is the building's shorter and earlier-constructed twin, the One-ifc.) The first was in Tomb Raider: The Cradle of Life in which Lara and Terry Sheridan leap off the still-under-construction building to escape their pursuers.
Trivia: The creepy way the Joker sucks at his cheeks was the result of Heath Ledger playing with the makeup they put on him. He did it constantly and the director thought it was so strange looking that they left it in as a character idiosyncrasy.
Trivia: Heath Ledger was given an advanced screening of the opening bank heist scene. That six minute sequence was the only part of the completed film he saw before his death.
Trivia: The film was delivered to some theaters under the name "Oliver's Army".
Trivia: Heath Ledger became very attached to his role. He would show up on the set, in full costume, even on the days he wasn't filming.
Trivia: Dwight Yoakam turned down two roles in this movie. Originally he was offered the part of a cop; then he was offered to play a banker who had dealings with the Joker (Heath Ledger). Yoakam passed on both roles because he was working on a Buck Owens tribute album.
Answer: It's habit, and a sensible one at that. When he's in the mask, when he's being Batman, he uses the voice, even if the person he's with knows who he is. If he drops back to his normal voice with some people, it sets the precedent for using it while wearing the cowl, which means that he's more likely to slip up and use it around people who don't know, potentially revealing his true identity. If he sticks rigidly to using the voice when kitted up as Batman, regardless of situation, it minimises that possibility.
Tailkinker ★