• James Franco(Oz) was 33 at the time of filming. Frank Morgan(The Wizard in the original) was 48 during filming of the 1939 film; Age difference: 15 years
• Mila Kunis(Theodora) 27-28 years old. Margaret Hamilton(Wicked Witch of the West)35-36. Age difference: 8 years
• Michelle Williams(Glinda) 30-31. Billie Burke(Glinda from the 1939 film)54. Age difference: 23-24 years

Therefore, it is somewhat difficult (if not impossible) to calculate or even estimate the length of time between this movie and the 1939 film take place.

This is a prequel to L. Frank Baum's book, The Wonderful Wizard of Oz.

This version is not canon to Wicked or to the 1939 MGM musical film. It is canon to Baum's books. So Elphaba does not appear. In this movie, she is replaced with Evanora, to make us think that she's the Wicked Witch of the East and Theodora is the Wicked Witch of the West.

The ruby slippers and various other elements were inventions of the 1939 MGM film. Due to legal issues, Disney was not able to use these elements. This extended to small things like the spiral yellow brick road design, to what color green the Wicked Witch's skin could be.

In the books, Glinda is the Witch of the South. When Dorothy first arrives in Oz she meets the witch of the North first and Glinda at the end. The 1939 film combined the two witches. Oz the great and Powerful restores Glinda to being the Witch of the South with the witch of the North unknown/unmentioned in the film.

It is thought that it only begins to affect Theordora when she starts to become evil, she shows no fear of it before. Hence her tears hurt her because she is beginning to have dark desires, the water is "washing away her sins". It's a foreshadowing of the Wicked Witch of the West in The Wizard of Oz who melted away at a bucket of water.