* Caterpie is the first of a main character's Pokémon who had its design changed to match new official game art, despite being introduced before the change. In a flashback in ''[[DP080|The Thief That Keeps on Thieving!]]'', Caterpie's mouth was green as per the official Generation III game art. However, when it was first introduced, Caterpie's mouth was yellow as per the official Generation I game art.
* Butterfree was the first of Ash's Pokémon to debut before his capture episode, the first one caught, the first he evolved, the first one to reach his final form, the first he traded (although he was traded back), and the first he released.
* In the English [[List of Electric Tale of Pikachu monthly issues|monthly issue publication]] of [[The Electric Tale of Pikachu]], the order of ''[[ET02|Play Misty For Me]]'' and ''[[ET03|Clefairy Tale]]'' is reversed. This creates a continuity error, as Butterfree appears in ''Clefairy Tale'', even though he supposedly doesn't evolve until one chapter later.
* Butterfree was Ash's fastest evolving Pokémon, reaching his final evolution two episodes after his debut.