Dawson Casting: Curiously zigzagged. Played straight in the case of Christian Bale for college-aged Bruce, and (ironically) inverted in the case of Katie Holmes as present-time Rachel (the character is supposed to be around 30, but Holmes was still in her early 20's in 2005).
Under Age Casting: Katie Holmes played an assistant district attorney despite being 26 years old and looking to be about 23. She should still be in law school by all accounts. Aside from that, she was romantically involved with Christian Bale who is older by a decent amount.
To top this, according to the original script Holmes's character is supposed to be some two or three years older than Bale's, to justify her being an intern at the DA office when he's still an undergrad. In real life, Bale is some five years older than Katie Holmes.
If she'd gone to law school straight out of college, she'd have graduated at 24 or 25. The only thing unlikely given her youth and inexperience is that she'd be handling cases—especially major, high-profile ones—on her own, but she'd still be able to work in the DA's office. It's not as much a stretch as other examples.
In The Dark Knight, she is replaced by Maggie Gyllenhaal who appears only slightly older than Holmes (indeed, she is a year older). In that film, she was still the assistant DA in a love triangle between the aforementioned Bale and the even older Aaron Eckhart's Harvey Dent.
The numerous proposals for a fifth Batman film that were bandied about for the better part of a decade, before Warner Bros. settled on a Continuity Reboot instead. See this page for more information.
The Wachowskis were given the choice of directing this movie or their sequels to The Matrix.
Word of God: Going by Word of God, comics canon, and the novelization, the Nolanverse Bruce Wayne was born on February 19, 1977 (1980 in the novelization); his parents were killed on June 26, 1988; their killer is killed and Bruce himself begins his seven-year odyssey on February 20, 2000; Henri Ducard discovered Bruce in early 2006; his training with the League of Shadows went on for about a year, culminating in the final test on January 17, 2007; Bruce boards a plane back to Gotham on January 21, 2007, arriving the next day; the film's story picks up on February 1, 2007, as Crane recommends that Victor Zsasz be moved to Arkham; the Batman makes his first appearance and serves up Carmine Falcone on Valentine's Day, with the case against Falcone going forward the next day; Falcone is driven insane on the 17th, and the Batman is poisoned by Crane that night; the climax takes place on February 19, 2007; Lucius Fox becomes the CEO of Wayne Enterprises the next day... and the final scene takes place on December 1, 2007.