Delia should've never mentioned Ash's father back in episode 2...
Exactly. Its the same thing as all the real animals we saw back in Season 1.
When Kanto was airing the writers had no idea at the time that this would be a 10 year+ anime, so some of the things they said or did during the first season ended up disappearing.
One of those original interviews said that Pokemon was only going to go on for 1 year and a half, and the only reason it became a real series is because of how popular it was.