The Mareep/Flaaafy line of Pokemon are sheep that are electric types. This is a reference to the novel "Do Androids Dream Of Electric Sheep?" The novel was the inspiration for the film Der Blade Runner (1982).
Initially this was intended to be the last Pokemon game.
Originally planned for a 1997 release.
In the game's code, there are various pieces of unused dialogue that refer to an item called "Sweet Honey." This implies that the honey mechanic was planned but scrapped to return later in Generation IV.
Early screen shots indicate a skateboard was going to be included as a transport but it was not included in the final version.