Some films require more work on the audience's part than others. Sitting through the latest Fast & Furious sequel obviously makes your head hurt less than something from David Lynch or one of the many directors he's inspired over the years.
The sheer volume of movies that make no sense thanks to gaping plotholes, convoluted narratives and clunky editing is higher than you might think, but there are places you can turn when you can't unravel the celluloid mess yourself - the internet.
In a world of online message boards and social media, every film is now backed by countless fan theories, ranging from entertainingly zany to entirely plausible, and some of them have even been endorsed by the filmmakers themselves.
Stan Lee is an omnipresent alien in the Marvel Cinematic Universe? Of course he is. The peddler from the beginning of Aladdin is actually the Genie? Obviously.
But sometimes fan theories go one better than just being on the money. There are movies out there that simply don't make sense without them...