Factual error: In the fourth floor of the Celadon Department Store, there's a guy who says that he's getting a Poke Doll for the Copycat of Cerulean City. Too bad that the Copycat actually is from Saffron City.
Other mistake: Go to the Day-Care Man. When he asks you if you want him to care a Pokemon for you, answer YES, but in the Pokemon list, press B to cancel. He'll say "All right then, Come again." However, the "Come" shouldn't be capitalized, it should be "come". This happens because this is a shared text, so when you answer NO to his question, he'll say "Come again", and that's why it is capitalized for this text. However, it is still a mistake. This was made due to a similar text error in Red/Blue, but this mistake was created.