L. Frank Baum, who flourished around 1900, is acknowledged as the author of The Wizard of Oz in the story's universe. Yet the viewer is asked to consider that Elizabeth Haskens is really Dorothy Gale from the story, even though she is only 12 in 2011. There is no indication that time travel exists in the movie's universe.
The Scarecrow and the Tin Man have to travel from New Jersey to Kansas with no supernatural assistance. Yet when in Kansas they seem to have the power to magically appear, and then vanish from, a locked library in the orphanage.
The Lion covers the escape of the Scarecrow and Tin Man in the balloon, by engaging the Flying Monkeys in unarmed combat on the ground. This defeats the purpose of being a *Flying* Monkey.