I suspect it is. It’s also a shout-out to the 1985 Disney film, Return to Oz, which was somewhere between a sequel to the 1939 MGM film and a dark, scary combination of the next two books (The Marvelous Land of Oz and Ozma of Oz).
That film starts with Dorothy being taken to a hospital to have primitive late Victorian/Edwardian shock therapy for her Oz delusions. She meets another girl there who winds up being Princess Ozma in Oz. This was not from the books, where Oz was always treated as 100% real; the movie made that slightly ambiguous, though less “it was all a dream” than Judy Garland’s film.
Keeper of Belle's Gold magic, sand dollar, cloaks, purple FTL outfit, spell scroll, library key, copy of Romeo and Juliet, and cry-muffling pillow, Rumple's doll, overcoat, and strength, and The Timeline. My spreadsheet: https://drive.google.com/file/d/0B6r8CySCCWd9R0RUNm4xR3RhMEU/view?usp=sharing