* AwesomeDearBoy: TimDaly said the reason he signed on to do Superman's voice in this series was because he thought it would be fun to play a superhero in a superhero cartoon. He later said he underestimated just how difficult voice acting for a superhero, especially one of Superman's stature, would be.
* CreatorBacklash:
** Although they all praise the performance of the voice-actors (especially ComicBook/JimmyOlsen's VA, David Kaufman), the production team has a very low opinion of "Superman's Pal", an episode of the third season [[ADayInTheLimelight focusing heavily on Jimmy Olsen]].
** They have a low opinion of "Little Big Head Man", which they felt tried and failed to recapture the success of the earlier Mxyzptlk episode.
* ExecutiveMeddling: [[WhatCouldHaveBeen Originally]], Ma and Pa Kent were supposed to die in ''Apokolips... Now!'', but DC said that if they were killed they would need to be brought back to life later. Unwilling to [[DeathIsCheap walk down that path]], the target was shifted to a different character.
* OffModel: The animation team did this intentionally, removing the "S" shield from Superman's cape in order to save themselves from having to animate how the shield would look as the cape rippled and moved.
* TheOtherDarrin:
** Gspltsnz was voiced by Sandra Bernhard in her first appearance and by Creator/JenniferHale in her second.
** Mala was voiced by Leslie Easterbrook in her first appearance and by Sarah Douglas in her second.
* RealLifeRelative: Ma and Pa Kent's voice actors (Mike Farrell and Shelley Fabares) are married in real life.
* UnintentionalPeriodPiece: The GreenLantern episode ''In Brightest Day'' shows struggling artist Kyle Rayner trying and failing to get his art out there the old fashioned way as he works for the Daily Planet Art Department. Today he would undoubtedly have a Tumbler or Twitter account and probably a DeviantArt account where he could promote his work on line.
* WhatCouldHaveBeen:
** An early idea was to have the series be a team-up show, with each episode featuring Superman partnering with different members of the Justice League. Timm did up concept art of a number of different heroes like Comicbook/{{Vixen}}, Mister Miracle, Orion and Lightray of the Comicbook/NewGods, Comicbook/TheQuestion, Nightshade (who would've sported a Comicbook/{{Psylocke}}-inspired outfit), and Comicbook/BlackLightning. An alternate concept piece featured other characters like TheFlash, Comicbook/WonderWoman, Comicbook/GreenLantern (Hal Jordan), Comicbook/BlueBeetle, Comicbook/PowerGirl and {{Hawkman}}, as well as villains like Star Sapphire, TheJoker, Comicbook/{{Catwoman}}, Captain Cold and Doctor Sivana. The idea was jettisoned out of fear that Superman would be overshadowed in his own show.
** The original plan for "Apokolips...Now!" had Ma and Pa Kent killed instead of [[spoiler: Dan Turpin]], but [[ExecutiveMeddling DC said they would need to bring the Kents back to life if that happened]]. Since Creator/BruceTimm wanted to avert DeathIsCheap the target character was switched.
** [[http://worldsfinestonline.com/WF/superman/backstage/interviews/dorkindyer.php The original, much darker plans]] for "Little Girl Lost" involved Superman discovering that Darkseid was turning humans into Parademons, with heavy [[ThoseWackyNazis Nazi overtones]] for the transformation camps, and the episode ended in the midst of a large scale battle on Apokolips. The authors do like the finished episode, but were very disappointed with the heavy backtracking after they had already been given the go-ahead for the initial plot.
** "Legacy" was intended to kick off a season's worth of episodes about Superman regaining the world's trust. However, a pushback and other projects (''WesternAnimation/BatmanBeyond'') led to it being produced as the finale instead, while the theme of public distrust for metahumans became an underlying plot thread in ''WesternAnimation/JusticeLeague''.
** Creator/ClancyBrown originally auditioned for the role of Superman before being cast as Lex Luthor, and according to the producers his initial reaction to being asked to play Luthor instead was "Am I ever gonna get to play a good guy?"
** Sherman Howard was considered for the role of Luthor, having previously played the character in "The Adventures of Superboy". According to Bruce Timm, Howard gave an impressive audition, and was nearly offered the role . . . until Clancy Brown walked in. Howard gave one-off performances as The Preserver and General Steppenwolf, and later voiced the Luthor-like Derek Powers in ''WesternAnimation/BatmanBeyond''.
** Paul Dini and Bruce Timm originally wanted to use Kara Zor-El as Comicbook/{{Supergirl}}, but they were denied by DC Comics due to the then-current "Superman is the ''only'' survivor of Krypton" edict. Although they went as close as they could get, with Kara being Clark's ''adopted'' cousin and from Krypton's "sister planet", Argo (a MythologyGag to that side of the House of El living in ''Argo'' City in the comics), essentially making her as close to Kryptonian as possible. An additional MythologyGag is her family name - Kara Zor-El's mother was named Allura ''In-Ze'', with said surname given to the show's interpretation of Kara.
** Lex's robotic TyrannosaurusRex was going to be given by Superman to Batman. This would have explained its appearance in the [[WesternAnimation/BatmanTheAnimatedSeries Batcave]].
*** The original ending to "A Little Piece of Home" would have also included Superman giving the piece of kryptonite from the episode to Batman for safe keeping.
** There were some art sketches of girls for the strip bar scene in ''World's Finest''. They wore nothing but black bikinis and long black leather boots. The final cut of the episode had the girls in flirty dresses instead.
** There were some thoughts of having Captain Marvel/Shazam appear in the series, possibly in a episode that would also introduce the Justice League, but a combination of rights issues and not wanting to introduce the Justice League out of nowhere put an end to it.
** A WonderWoman guest appearance was pitched but never materialized.
** Cat Grant was originally meant to be part of the main cast and even had a character design done up for her but she was dropped in favor of Angela Chen. Grant's design reportedly can still be seen in the series in various scenes. Had she been retained for the cast Cat would have served as a rival to Lois for Clark/Superman.

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