1st episode vs. 2nd episode -- different apartments!

One of the most famous examples was "Hangin' with Mr. Cooper", where the pilot was shot on the set of "Growing Pains" which was just ending it's run on ABC. Alan Thicke and Mark Curry even made some jokes about "Growing Pains" in the beginning of the pilot. Unfortunately, that exchange was one of the highlights of the entire series.

There was also the Cunningham house on "Happy Days" that change dramatically a few episodes into the first season.

Nothing's Gonna Change My World - The Beatles

I don't know if I'm the only one, but I always thought that after the pilot and Coco's decision to go live with Sarah the woman decided to move somewhere else bigger! This can be explained by the fact that the big apartment made out of a slaughterhouse looks pretty unfurnitured and that explains why Coco's room doesn't still exist and why their father comes in with that horrible sofa. I remember that in the next episode, the furniture changes another time.

I know it's a big change, but I think Amy did know what she was doing. She wanted to give the girls a house that almost looked like a 'stage'. You know what I mean? Give them space to be theatrical. The apartment where she lives in the pilot looks more like the house where the Gilmore girls lived.