The rise of the internet and movie chat forums has given birth to about a million half-baked fan theories. Nearly every week someone seems to propose a "shocking" theory about a popular movie, one that people either get excited about or roll their eyes at.
Now, in some rare cases these arguments can actually be well argued and intelligent. The stronger theories base themselves on actual evidence contained in the narrative, instead of imposing their viewpoint onto the story.
For example, one reading of Blade Runner has Deckard being a replicant implanted with the memories of crippled Blade Runner Gaff. This explains Gaff's open disdain towards him, but when Deckard finishes the assignment Gaff compliments him on doing "A man's job". As a reward Gaff lets Rachel live, but leaves behind an origami unicorn to let Deckard know the truth. This reading isn't airtight but the movie supports it.
Most theories are easily dismissed however, as they rely on flimsy evidence or flat out ignore the details that contradict them. Alas even the dumb ones can take root, as these eight theories will prove. Each one can be debunked by simply examining the film itself, which apparently most of these theories failed to do.