One think I didn't realize until my daughter and I read the book together: in the book there were two good witches, the witch of the North (the first one Dorothy meets after landing on the witch of the East), and the witch of the South (the one that tells her she can use the shoes to get home). The movie combined the two characters. Then they had to come up with a reason why the good witch didn't immediately tell Dorothy to click her heels together and go home. In the book, only the Witch of the South knew this.