And more Batman Begins/Dark Knight trivia:
Christian Bale had previously screen tested and was considered for the role of Robin in Batman Forever (1995).
Kurt Russell and Dennis Quaid were considered for the role of James Gordon.
Viggo Mortensen turned down Liam Neeson's role. Daniel Day-Lewis was also approached.
Anthony Hopkins was offered the role of Alfred but declined.
Laurence Fishburne was considered for the role of Lucius Fox.
Christian Bale's trailer didn't have his name on the door but said "Bruce Wayne" instead.
Due to his part in Maquinista, El (2004) (aka The Machinist), Christian Bale was vastly underweight (about 120 pounds on his 6 foot+ frame) when he was under consideration for the part. After being cast, he was told to become as "big as you could be" by Christopher Nolan. Bale underwent a dietary and exercise regimen and ending up weighing about 220 pounds (about 40 pounds above his normal weight). It was decided that Bale had became too large (friends of his on the film's crew dubbed him "Fatman") and he quickly shed about 20 pounds to have leaner, more muscular frame.
Matt Damon was Christopher Nolan's first choice for the role of Harvey Dent but turned it down. Before Aaron Eckhart was cast in the part, other actors considered included Hugh Jackman, Ryan Phillippe, Liev Schreiber, Jake Gyllenhaal and Josh Lucas.
As a joke, one bat suit was made with nipples, as in Batman & Robin (1997). It was presented to Christian Bale as the real bat suit, but he knew instantly it was a joke, having seen a few design pictures during preproduction. He did pose for some publicity photos in the "nipple" suit.
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 A Clockwork Orange (1971)'s Alex and Sid Vicious.
It's Sir Michael Caine's opinion that Heath Ledger beat the odds and topped Jack Nicholson's Joker from Batman (1989): "Jack was like a clown figure, benign but wicked, maybe a killer old uncle. He could be funny and make you laugh. Heath's gone in a completely different direction to Jack, he's like a really scary psychopath. He's a lovely guy and his Joker is going to be a hell of a revelation in this picture." Caine bases this belief on a scene where the Joker pays a visit to Bruce Wayne's penthouse. He'd never met Ledger before, so when Ledger arrived and performed he gave Caine such a fright he forgot his lines.