Koffing and Wheezing's original prototype names were NY and LA referring to the polluted cities of New York and Los Angeles.
Early concept art indicated a female was going to be included as a player character.
The Blue version of the game was originally released in Japan through CoroCoro Comics.
Cerulean Cave was slightly redesigned for the U.S. release of Red and Blue for concern that the dungeon would be too difficult for American players.
Rhydon was the first Pokemon designed and programmed into the game and Victreebel was the last, thus giving Victreebel the highest index number of any non-glitch Pokemon.