Ascended Extra: Verde was originally only created for two scenes, but the author liked him enough to expand him to recurring villain.
Throw It In: The poker scene and Right comforting Jade in chapter 14 weren't part of the original outline of the chapter, but were added spur of the moment by the author.
Per Word of God, Tarakudo's brief cameo in the final scene of chapter 16 was a last minute addition.
What Could Have Been: Jade's father Shen wasn't originally going to show up in the story; rather than his appearance, the events of the Mexico City chapter were supposed to lead directly into Viper's abduction and transformation. Instead, the author decided to push that back a chapter in order to give Jade a chance to call the old man out.
Also, the author had originally planned the Shadowkhan as a race enslaved by the Oni, but in the end scrapped the idea.