Plot hole and BIG one at that
Ok before Joy falls into the abyss of forgotten memories this was the layout of the area:
Goofball Island
Friendship Island
Imagination Land
Hockey Island
Honesty Island
and finally Family Island.
But after Joy escapes the abyss not only are both she and Sadness back at the beginning of Imagination Land but Now Imagination Land is right outside Family Island (this is most oblivious when she's getting ready to do the boyfriend/trampoline trick).