The episode "His Master's Voice" is loosely based off of "The Shadow Over Innsmouth" by Lovecraft. In one scene where Kari walks pass a sign, it spells Insumausu (Innsmouth) in Digicode. The "Scubamon" in the episode are based off the Deep Ones featured in the tale.
Actor-Shared Background: A mild/tangential example: according to the footnotes in the booklet for Digimon Adventure 02's DVD box, supposedly the reason for Ken and Miyako getting married in the finale is that their voice actresses (Romi Park and Rio Natsuki) got along very well with each other.
The two head writers for this series Genki Yoshimura and Atsushi Maekawa had two very different styles of writing, Maekawa's being story driven light-hearted stories, and Yoshimura's being character driven darker stories, both were told to write in their own preferred styles. This lead to them not seeing eye to eye on how the story should go, which resulted in a lot of fillers, to cover up for the time where they couldn't come to an agreement.
Meanwhile, the head writer for Adventure, Satoru Nishizono, left the Digimon project because he didn't want for a sequel to his series to be made.
Much of the main staff including Chiaki Konaka couldn't stand the executive meddling anymore, and so were ready to break their contracts and leave the project, but Bandai, unwilling to let them do this, gave them their own series, to mess around with instead.
Fake Brit: While not actually British, being a Digimon and all, Hawkmon has a British accent in the English dub, while his voice actor, Neil Kaplan, is American.
Fan Nickname: The fake Divermon are referred by fans as the "Digital Deep Ones".
The decision to not make him develop as a character.
The entire season owes its existence to this, as the head writer of Adventure didn't want to create a sequel.
On the other side of the Pacific, Jeff Nimoy stated that Digimon: The Movie was supposed to just feature the first two movies, but higher ups demanded he add the third movie in, which he wanted to be shown as a TV special.
In the series itself, he and his cowriter Bob Buchholz were instructed by Fox Kids to make the series "funnier" which annoyed a lot of fans, eventually Jeff and Bob left due to frustrations with Fox's demands, Fox Kids must of backed off because the final 8 episodes of the season were noticably less Gag Dub.
God Never Said That: A particularly widespread rumor in the fandom is that originally, the Distant Finale's couples would include TK/Kari and Izzy/Mimi along with the canon Sora/Matt and Ken/Yolei. The fans who talked about this kept citing an alleged interview with someone who worked on the show, but no evidence of that interview has been found.
Doug Erholtz replaced Wendee Lee as T.K. in the dub, but this is justified due to T.K. now being 4 years older. In the Japanese version, Taisuke Yamamoto replaced Hiroko Konishi after the latter retired from voice acting and subsequently became an Unperson to the series.
Due to Jeff Nimoy leaving the show due to Executive Meddling, R. Martin Klein took over as Tentomon for the last few episodes.
Jason Spisak replaced Joshua Seth as Tai Kamiya and Bridget Hoffman replaced Laura Summers as Patamon in Revenge of Diaboromon. These were the only major instances of the trope despite Adventure 02 having finished airing four years before and Saban Entertainment no longer being involved in the dubbing. It's an Actor Allusion in Hoffman's case, because she voiced Patamon in Digimon Frontier.
There were a few cases of Digimon who had only one line in the movie (i.e., Gabumon, Hawkmon) where Jeff Nimoy impersonated the actor, simply because the budget wasn't big enough to bring Kirk Thornton or Neil Kaplan for a single line each.
Refitted for Sequel: By director Hiroyuki Kakudo's admission, the infamous epilogue was originally planned for the first series.
Screwed by the Network: During the Dutch broadcast of this anime, the Dutch Fox Kids had the rather strange policy of refusing to air episodes featuring snow or Christmas outside the respective season. Unfortunately, many important episodes, including the finale, take place during Christmas or snowy weather. This means the Dutch audience was unable to see how the series ended during its original run.
It's unknown who did the voice for Ken's older brother in the English dub, but in the original, both are voiced by Romi Park, who spends the entirety of episode 23 doing this (as the episode focuses on Ken and his past with his brother).
In the original Japanese version, Megumi Urawa voices both Iori/Cody and his partner Armadimon. This is the first, and to date only, time that a Chosen Child and their Digimon partner have been voiced by the same person.
Not the only example of a Chosen Child and their sibling(s): having the same seiyū: Miyako/Yolei and her sisters (Momoe and Chizuru) are all voiced by Rio Natsuki.
In English, Prince also does the voice of Veemon. The trope gets played as early as episode 2, when the Emperor taunts the captured Digimon.
Yolei's dub actress also voices Biyomon.
In the Swedish dub, both Ken and Matt are voiced by Leo Hallerstam. Which proves amusing in the World Tour Episode.
Technology Marches On: Averted - the show overestimated something like the D-Terminal showing up in 2002/2003.
Nodded to in the movie, Diaboromon Strikes Back. In Diablomon's first appearance, Our War Game, he manages to cripple Taichi and Koushirou by infiltrating the phone company and clogging everyone's modem. In DSB, Daisuke at one point nearly breaks into the Internet by borrowing some stranger on the street's laptop.
The Dark Ocean was introduced by guest writer Chiaki Konaka and was originally supposed to be used as a larger plot point. The rest of the writers then proceeded to mostly ignore it.
Not to mention Daemon. The original plan was for him to be a Big Bad, but it never was able to happen.
Co-Head Writer of season 2 Jeff Nimoy did not want to combine all 3 movies and just wanted to combine the first two into a feature length film and release the third movie straight to video or as a tv special (with the older kids being kidnapped subplot and all the other major edits intact) but higher ups at Fox forced them to combine all 3 movies, resulting in a confusing mess and the third movie being hacked to bits.
Early character design sketches in 02 showed a lot more alternate outfits Mimi would have. Thankfully, some of them didn't make it into the final draft, and the most unfortunate we got was the one with the Funny Afro.
On the first version of Fox Kids' movie website, Willis' name was left as "Wallace." Updated versions replaced his name with "Willis", seemingly indicating that the movie was initially going to keep his original name.
Really there is a lot of What Could Have Been this season, Bandai had created 8 armor evolutions (for each crest) for each partner Digimon, there was a digimental of kindness that Wormmon could use to become Bucchiemon.
For that matter, Ken was supposed to use the crest of Kindness to evolve Stingmon naturally before it got dropped in favor of Jogress evolution.
Also, at some point the digimon would've digivolved with both their main digimentals instead of just one. Hints of this can be seen in Sagitarrimon's design, which is clearly based on Flamedramon for the upper body and Raidramon for the lower body and head.
Arukenimon was going to be Sasoribellamon, with a scorpion theme.
Ken's name was originally going to be Ryo, but this was changed due to the Tag Tamers games' protagonist having the same name. He and his brother Osamu's names are respectively written as 賢 and 治, in a nod to then-current Fuji TV producer Kenji Shimizu (賢治).
In the English dub, Sora and Matt's sudden dating. The dub clearly favored Tai/Sora with constant teasing (including giving Tai an unrequited crush on Sora) while Matt/Sora got the short end of the stick with Matt acting like a jerkass. Comments from the original writer of Digimon Adventure indicate his general distaste for the pairing of male and female leads and he'd originally meant for Yamato and Sora to have a much stronger bond and foreshadowing of their eventual marriage. note That said, there was still enough wiggle room for legitimate dissent of opinion. The Japanese seiyuu for Sora and Gabumon (!) indicated in personal comments their surprise when it turned out Sora and Yamato would become a new couple, with Sora's actress indicating she figured Sora could be more open and straightforward around Taichi.
Matt being an astronaut in the epilogue is actually a leftover plot thread from an idea abandoned in production — a third year of Digimon Adventure was supposed to have enemies from space, but it was never picked up and we got Digimon Tamers instead.