First instance of a 'shiny' Pokemon in the series.
In the dub, Brock says that Ash raised Butterfree to be courageous and that he believes Ash has shown himself to be courageous too, to which Ash thanks him. In the original version, he instead says that people can take care of Pokémon but cannot reproduce them, to which Ash agrees.
In this episode, Team Rocket's motto is ripped off for the first time.
Ash releases Butterfree.
This is the first episode of the anime to have a boss fantasy.