At the end of the series, it is revealed that time in Oz moves very much differently than on Earth. Since Dorothy was in Oz for 10 Ozian Days, or around 10 Earth Minutes, that means that an Earth Minute is a day in Oz. If we go by the lore of Emerald City happening after the Beast Forever attacked it twenty years ago, this brings up a question: 20 Earth Years, or 20 Ozian Years?
If it is twenty Earth Years, then it would be around 1.051e+7 Earth Minutes, or 1.051e+7 Ozian Days, which in turn is 28794 and a half Ozian Years! This cannot be right since that would mean that The Wizard, Jack, Tip, Jane, and pretty much any non-witch in Oz are long-dead. Also, Oz would be more technologically advanced, where as in the show, it is more like a mixture of The Middle Ages and Victorian times.
If it is twenty Ozian Years, then that would be 7300 Ozian Days, or 7300 Earth Minutes, which would total to... five Earth Days. This is wrong since Dorothy would only be around a week old.
The fact that the Wizard goes through the trouble of collaborating with East to create The Prison of the Abject to house all the magic users seems at first to be a case of Why Don't Ya Just Shoot Him?, until one remembers that in Oz only a witch can kill a witch. So capital punishment isn't really an option for the Wizard's regime.
The East Witch's comment to Dorothy about how 'nothing good comes from the sky'. Recall that in the original novels, the Wizard first came to Oz on a hot air balloon.
Towards the end of "Everybody Lies" Dorothy enters the Wizards chambers and notes that he's playing Pink Floyd. Specifically the song playing, "Breathe", is from their most famous album The Dark Side of the Moon and syncs up with The Wizard of Oz if both are played at the same time. Some of the lyrics to "Breathe" seem to narrate the Wizard's journey to Oz if listened closely:
Look around, choose your own ground (The Wizard choosing to stay in Oz, eventually becoming the new ruler against Karen's protests)
Long you live and high you fly (Previously came from nothing, reigning over Oz for twenty years)
All you touch and all you see is all your life will ever be (The Wizard devoting his life to ruling Oz with science)
Balanced on the biggest wave, you race towards an early grave (Possible foreshadowing of his demise?)
This proves prophetic at the end of season one when Frank is killed.
The ending of season one, where Lucas is sent by Jane to bring Dorothy back to Oz becomes this with the reveal that time moves different in Oz. Dorothy was gone for up to ten days, but once she comes back home, only ten minutes have passed in real-time. She's home for at least a day before Lucas returns. If ten minutes of Earth time = 10 days of Ozian time, how much time has passed? And more importantly, how long has the Beast Forever been roaming Oz, and how much damage has it already done?