Ferris Bueller's Day Off: one theory has it that cocky, confident Ferris isn't real, but a manifestation of the repressed id of the put-upon Cameron. It's not especially compelling, given the amount of time we see Ferris on his own, and with his girlfriend, and with his sister and parents.
Grease: Sandy drowns on the beach at the start of the film, the action taking place during her last moments alive, and the ending, with her and Danny flying off in their car Chitty Chitty Bang Bang-style, represents her ascension to heaven.
The Wizard of Oz: In the film, did Glinda delay telling Dorothy about how she could get home so Dorothy would kill the other evil Witch, the Wizard would depart and "good" Glinda would be the one magical being left, with all the power? Is it a feminist story, given the women in the story are the ones with agency and the men are damaged beings?
Titanic: Jack is a time traveller sent to save Rose from jumping off the ship since if she did, they would stop to look for her and the Titanic would not hit the iceberg and sink, thus altering the timeline of the world irrevocably. Jack knows about things that weren't yet around 1912 like the roller coaster that wouldn't be on the Santa Monica Pier until 1917. It couldn't simply be that writer-director James Cameron made the odd mistake, right?
Winnie the Pooh: Christopher Robin is schizophrenic and the other characters are manifestations of his imagination showing his struggles to learn how to deal with the world. Pooh has ADHD, OCD, and other impulsive tendencies, Eeyore suffers from clinical depression, Piglet has generalised anxiety disorder, Owl is dyslexic, and Tigger has ADHD.
And there are many more:Frozenis Disney's version of The Shining (a kid with supernatural power, houses with forbidden rooms, ice and snow), Harry Potter went nuts while locked in the cupboard and the whole story is in his head, the title character in Finding Nemo never existed but was made up by Marlin who was shattered by his wife and kids' death ("nemo" is "no one" in Latin)...
It's all certainly imaginative. And occasionally it makes you think.