Duncan Jones was offered the film, but turned it down, not because he didn't like the Alex Garland script (Jones said it was great), but because he had such a strong idea of what he wanted to do with a Dredd movie, that he felt he could not bring himself to take it on and not do it his way.
Judge Joe Dredd is a fictional character whose comic strip in the British science fiction anthology 2000 AD is the magazine's longest running, having been featured there since its second issue in 1977. Dredd is a law enforcement officer in a violent North American city of the future where uniformed Judges combine the powers of police, judge, jury and executioner. Dredd and his fellow Judges are empowered to arrest, sentence, and even execute criminals on the spot. The character was created by writer John Wagner and artist Carlos Ezquerra, although editor Pat Mills also deserves some credit for early development.
In the Judge Dredd comic strip, all blocks are given names relevant to some form of connection to the creators, the inspiration for the characters/story or current affairs at the time of writing. The nearest block to Peach Trees, where the film is set, is 'Sternhammer'- which is visible in the opening scenes and at the end of the film. It is also referred to as being where one of the Ma-Ma clan's rivals are based. Wulf Sternhammer was a popular recurring character in the Strontium Dog comic strip in 2000 AD, which shared many writers to Judge Dredd and has even had cross over stories.
Karl Urban's voice for Dredd is comparable to that of Clint Eastwood. The character of Judge Dredd is in fact partly based on Eastwood's character of Dirty Harry Callahan from the film Dirty Harry, while the initial look of the character was partly inspired by the original poster art depicting the David Carradine character of Frankenstein from Roger Corman's original Death Race 2000. In the comics, as a tribute to Eastwood's strong influence on the character, Judge Dredd lives in Rowdy Yates Block, which was the name of the character Eastwood played in the TV series Rawhide.
The Chief Judge is not referred to by name in the film. In appearance she is a combination of Chief Judges MacGruder and Silver, and the setting (the boundary wall and the Fergee memorials are both referred to) would place the time of the film in Mega City history as Macgruder's first period in office.
In the scene just before Judge Dredd and Anderson travel to Peach Trees, all of the crimes in Mega City 1 are shown on computer screens in the Hall of Justice; one of the first screens shows a crime being assigned to Judge Hershey. Judge Hershey is one of the main characters from Judge Dredd.
When the movie shows the comm interface map of the city, the ticker reads that Stumm Gas is being deployed to disrupt rioters at the Fergee Memorial. Later in the film Judge Hershey is mentioned on the ticker to be responding to the riot. Stumm Gas and Judge Hershey are both references to the 2000 AD comics. The Fergee Memorial is another nod to a character that was depicted in the original 2000AD Judge Dredd comic strip, taken from the classic comic storyline The Day The Law Died. It is not a reference to the singer and actress of a similar name, as is sometimes mistakenly believed.
Alex Garland pitched in this project when learning that his friends, producers Andrew Macdonald and Allon Reich were interested in venturing into big budget projects. It took Macdonald and Reich two years to get the film rights sorted out as the original rights went through several owners after Disney produced the Stallone version.
There are several references to "fatties" from the comic book (group of extremely obese people, many so obese they require a wheel under their stomach to move) - the first shooting victim of the escaping car chase occupant was a "fattie" lying next to his stomach wheel, there is also graffiti on the first shots of the skate ramp reads "Fatties rule!" and a cut to an extremely obese man during lock-down with a shirt with "fatties" on the front.
In Ma-Ma's penthouse there is a Judge's helmet hanging on her wall with a length of gold chain attached to it, a nod to the comic design of Judge Dredd where the gold chain would link the badge to the uniform collar
The large building with shutters over its sides that Dredd drives past in the initial chase, is John Vorster Square police station. It is the station where the political activist Steve Biko died during police interrogation in 1977 and the shutters are bullet traps to stop terrorist attacks. The Hall of Justice is actually the inside of the main campus for The University of Johannesburg - the old Rand Afrikaans University campus. Its massive Concrete Hallways are notoriously cold during wintertime.
In one scene there is a poster for the fictional film Krysler's Mark, a reference to Owen Krysler the Judge Child in the classic Dredd story written by John Wagner which introduced the Angel Gang. The poster says the film is directed by Ulf Suhrmuller, who is found out during the closing credits to be a real person and is listed as the Art Department Runner.
The trivia item below may give away important plot points.
There were three treatments that Alex Garland wrote before settling for the present story. The first treatment - the Dark Judges treatment features the encounter between Dredd and a rival judge by the name of Judge Death. However, Garland abandoned it after a year's work and 16 drafts on the story admitting that he couldn't crack much on that storyline. The second treatment is related to the Dredd and Cursed Earth storyline but was abandoned for the similar reason. The third treatment was an adaptation of the pro-democracy terrorists attacking the judges storyline but Garland felt that story and his ideas towards it were too grandiose in nature but stated that treatment would have been the third part of a trilogy, if there would be one. The final script that he wrote was based one of the punchier short stories in the vein of cop movies e.g Training Day. John Wagner described the script as correcting the mistake in the Stallone-starred version that was being too sweeping.