Haha, this episode isn't just bad. It's bizarre. Little Carrie is in everyone's way, and with Pa off on a get-rich trip, she enters a world that is Alice in Wonderland-esque. Giant spiders, giant berries, and an ethereal girl that bears a striking likeness to her named "Alissa" becomes her companion.
The subplot with Pa and Mr. Garvey on a trip at least are standard Little House, but Carrie's story line just doesn't even fit the series, it's so strange. A minor point, but I didn't like how impatient Ma got with Carrie when she tried to help her with the laundry. Certainly she had lost her cool a bit with Carrie's carelessness, but the tone in which she tells her to "go fishing, Carrie," reminds me more of the mother in the horror film Carrie than sweet Ma Ingalls. While this episode was painful, there are other ones in the series I ranked as guiltier than this of wasting a perfectly good hour of one's life: