In the beginning of what is supposed to be a sequel to Wizard of Oz we are led to believe Dorthy's visit to Oz was actually a hallucination brought on by mental illness. But after escaping a psychiatric hospital where she's sent for electroshock therapy, she winds up back in what has become an incredibly bleak post-apocalyptic Emerald City. The yellow brick road is rubble and citizens are crumbling plaster statues. I was six when I saw this and never cried so hard in my life.
One of the countless disturbing scenes:
Reviews written at the time warned parents not to take young children. It's kind like a One who Flew over the Cuckoo's Nest themed bad acid trip for kids.