Oz the Great and Powerful (2013) proves that.
Actually ... When you follow the Red Brick Road, you end up in the third act of Inception. OtGaP is simply another dream within a dream, etc trope.
That is, if you consider Oz the Great and Powerful to be "in continuity" with the Wizard of Oz movie.
I do. Both movies complement each other.
In the 1939 film it had to have been a dream. How else could the characters like the flying witch, the talking scarecrow, the tin man, etc. have been real?
"Return to Oz" proved it.
I never saw it. Was it any good?
Different takes on a book. Not related.