Judy Garland needed special wardrobe to appear younger
Even though Judy Garland was only 16 when she played the role of Dorothy the producers wanted her to look younger. So, they made Garland wear a corset to shrink her frame down. This is why online college degree courses in feminism exist.
The famous ruby red slippers are actually inaccurate!
In the original Oz books the famous slippers that Dorothy clicks together are silver. MGM wanted something a little more colorful to show off their new cameras and ruby red was chosen. Good decision at the end of the day!