Some more backstory (not that it’s needed for the film to be enjoyable, but I do think this adds value for some, to make the film even more enjoyable…):
So there was a time, not very long ago, when some neuroscientists seemed to insist dreams held no meaning. 
Listening to podcasts now, it seems hard science is getting much better at ‘seeing’ what we’re dreaming, and finally confidently linking some dreams to our past experiences, and emotional processing etc. 
What neuroscience still needs to do much better, is to start looking at the mythological content of dreams – in terms of symbols AND also in terms of the stories we dream – and matching those to our shared mythology.