In case the show wasn't a success, the crew made an alternate ending for "The Legend of the DigiDestined" where after Devimon was defeated, Gennai would appear and send the kids back home. If that ending was to happen, Kari would have never existed, and the overall franchise would not have been possible.
When Apocalymon was screaming, he self-mutilated himself before the kids (Hence Mimi covering her eyes). However, he regenerated with green bloodstains on him still. Despite his treatment in the dub, Apocalymon was more disturbed with a sense of vigilante justice for his pain. He also referred to himself as "We", likely as he had no one to talk too in the void and that he was created from the data of Digimon who were wipeout for being unable to evolve and exist in the next age of the Digital World (episode 1.53 "Now Apocalymon Part 1").
In early story concepts of Season 3, the character Juri Kato (renamed Jeri Katou in the English version) was only going to be a minor character and not become the focus of the destiny concept used by the D-Reaper late in the season. Juri's father was also going to be tied to the Yakuza in a prostitution ring leaving Juri to care for her younger sister.
Because of the September 11th terrorist attacks, ABC Family edited out MachineDramon using his giga cannon attack to explode the building at the end of this episode (episode 1.48 "My Sister's Keeper").