Tim Curry was initially cast as the voice of the Joker. After he recorded four episodes, his take on the role was deemed to be too scary, so the decision was made to recast and eventually the role went to Mark Hamill.
To create the eerie nighttime feeling, the background painters used dark paper instead of the traditional white. This also allowed them to save time from painting large portions of black color as most of the scenes are set at night. The animators coined the term "Dark Deco" for this art style.
When establishing Two-Face, the writers took the time to show his alter-ego first, Harvey Dent, in a number of episodes so the audience could get to know him better. That way, they were more shocked at his transformation from the upstanding Dent to the monstrous Two-Face. The writers believed this made him into one of the show's best characters, and his origin one of the show's best episodes.
All voice acting was, unlike most voice-over work, performed ensemble. This means that all the voice actors performed their lines in a room together, rather than at separate times in different locations. Mark Hamill was the only cast member allowed to perform his Joker voice while standing, to make it easier to infuse the character with the manic energy the role required. All the other actors did their voices sitting down.
Since the debut of this series, various elements have been adapted into the regular continuity of the Batman comics. These include the series' most popular original character, Harley Quinn, and the show's origin for Mr. Freeze.
When it came time to bring The Penguin into the show, Batman Returns (1992) had just gone into production. Warner Brothers insisted the animated version should reflect the one in the film, but they weren't allowed to release any pictures. Bruce W. Timm had to draw sketches on the set of the film and then adjust him accordingly for the cartoon.
The Scarecrow's voice actor Henry Polic II had problems with throat while playing Scarecrow in Episode "Dreams in Darkness." That is why his voice in Episode "Dreams in Darkness" is different from his voice in Episodes "Fear of Victory" and "Nothing to Fear." After the episode "Dreams in Darkness", the appearances of Scarecrow was reduced. Although Scarecrow appears in Episode "Trial", still Scarecrow has no dialogue in this episode. This was because Henry Pollic II was recuperating from throat surgery during this episode's production.
Harley Quinn's relationship with The Joker was intended as a Punch & Judy coupling, but with the roles reversed. She was initially a one-shot character but audiences took to her. She was brought back for more, and the writers even took the time to sketch a comic-book origin for Harley, to make her seem more real.
Harley Quinn was initially created for one episode, and was added to it almost at the last minute. In the episode "Joker's Favor," Joker was initially to disguise himself as a female model to serve as bait for a trap he was setting. Writers determined that posing as a woman would be below the Joker's ego, so they created Harley Quinn as his Henchwoman for the episode to keep the disguise.
After 14 years, "The Dark Knight's First Night", the rarely seen pilot promo reel developed for Warner Brothers by Bruce W. Timm and Eric Radomski, was included on the first DVD boxed set. Versions of the promo had surfaced in degraded bootleg form at comic conventions over the years, but was never intended for public viewing. Unfortunately, the actual Warner Brothers reel was not kept in the best condition either, appearing at around 105 seconds in length and having been converted from VHS. The original Audio track was lost over time and replaced with the show's main theme for the DVD.
The show's first opening sequence is essentially a remake of the pilot used to sell the show to Warner Bros. In the pilot, Batman foils a jewelry heist on a rooftop and leaves the robbers tied up for the police. The pilot can be seen as a special feature on Vol. 1 of the DVD collection.
The episodes "Heart of Steel" and "His Silicon Soul" feature a character named Dr. Carl Rossum, a robotics engineer who creates a series of human-like robots. The character's name is taken from the 1920s science fiction play "R.U.R. (Rossum's Universal Robots)" by Karel Capek, which introduced the word "robot" into the English language. In both episodes, Dr. Carl Rossum is voiced by William Sanderson, who played the Replicant creator J.F. Sebastian in Blade Runner (1982). As a reference to this, in the episode "Heart of Steel," Randa Dwayne's car has "RUR" on its license plate.
For a long time, the producers wanted to use Firefly, a character that uses fire as a weapon, but Fox said no completely because they did not allow any character to be threatened or harmed by fire. It wasn't until Batman moved to the WB that Firefly was able to be used.
A potentially story involving a Catwoman / Black Canary team-up was interrupted in mid-pitch to the FOX network by their demand, 'Where's Robin?' When the writers asked if they could omit Robin from just this one episode, FOX obliged by omitting the entire story.
Paul Dini has said that Harley Quinn was partly inspired by seeing Arleen Sorkin wearing a harlequin's costume in her role as Calliope Jones on an episode of the daytime drama Days of Our Lives (1965). As a result, Dini was subsequently inspired to cast Sorkin as the voice of Harlequin. In addition, Dini and Sorkin were college classmates together.
Although "On Leather Wings" is considered as the first episode, still the first episode that was aired on television and received the attention of the audience was Episode "The Cat and the Claw Part 1."
After every single storyboard, FOX would send the producers a long single spaced list of restrictions about five pages in length, on things they could not do for example; no child endangerment, no open wounds, no blood, no heavy gun violence, no strangling or neck grabs, no alcohol references, and no smoking. The FOX network was really picky, not just about the censorship, but just in terms of content and story. The network had many opinions on what the producers should and shouldn't be doing.
The FOX network, on the assumption that kids won't watch a kid's show unless kids are in it, soon began insisting that Robin be prominently featured in every episode. When FOX changed to title to "The Adventures of Batman and Robin" for Season 3, they laid down the law - no story premise was to be considered unless it was either a Robin story or one in which the Boy Wonder played a key role.
In Stu Hamilton's World's finest interview with 'Alan Burnett' qv) (one of the producers of this show), he revealed that he is a big Alfred Hitchcock fan. He was able to get John Vernon to play Rupert Thorne in this show. Roscoe Lee Browne was also cast for the role of Dr. Wakati in Episode "Time out of Joint." In Topaz (1969), John Vernon played Rico Parra and Roscoe Lee Browne played Philippe Dubois.
Robin's costume was modeled after Neal Adams redesigned Robin costume that Tim Drake wore in the comics, though the Robin symbol was changed to a regular non-italicized "R" to make sure people would know he's Dick Grayson. However, when Tim Drake was used his costume was redesigned with a Red, Yellow, and Black color scheme.
While working in this show, Bruce W. Timm and Story Editor Sean Catherine Derek strongly disagreed with each other. According to the Book "Batman Animated" Page 12, Sean Catherine Derek felt that Directors and Storyboard artists of this show were taking too many liberties with the scripts. Jules Dennis, Richard Mueller, and Sean Catherine Derek wrote the original script of Episode "The Forgotten." But Bruce Timm made several changes to the script. According to 'Animato' Magazine Issue #26, Timm put in the dream sequence with Bruce Wayne in the barracks where the multitudes of people are looking to Bruce for a handout, and he doesn't have enough money for them all, and they're surrounding him and suffocating him. Timm also completely changed the villain in the script of "The Forgotten" to a fat and revolting character who constantly eats.
1992-1995 Time Period of Batman (Batman Animated Series & Batman - Mask of the Phantasm) is also known as "Radomski Era", because of Director/Producer Eric Radomski's involvement with this show and Mask of the Phantasm. According to the Documentary "HBO First Look - Mask of the Phantasm", it was Eric Radomski who started using Black Papers opposed to traditional white papers.
Debated was the inspiration for The Joker in the original comic book, 'The Joker' was almost identical in appearance to the main character in The Man Who Laughs (1928). Almost all episodes featuring The Joker are taken from the film.