Oops! I forgot the Wizard got shot by Jane and I guess... died?
But yeah it's in 1x10. When the Wizard says that Dorothy's mother is in Oz (and I assumed he was talking about Jane).. then right after that is when Jane shoots him. And then her and Dorothy are talking and then Jane sends her back to Kansas. So it does really look like the wizard was telling the truth about Dorothy's mother being in Oz.
And all of what Jane was saying.. it seemed like she was Dorothy's mother. I don't think Jane would lie.