9. The John Connor Paradox - The Terminator
Time travel is always a tough nut to crack, and more often than not the films that best manage to weather the logical issues associated with timey-wimey shenanigans are those that actually embrace the contradictions.
And there's perhaps no better example of that than James Cameron's The Terminator, which of course follows soldier Kyle Reese (Michael Beihn) as he's sent back through time by human resistance leader John Connor to protect his mother Sarah (Linda Hamilton) and ensure that he himself is eventually born.
But the film's big twist is that Kyle and Sarah end up falling in love and conceiving John themselves, creating a brain-breaking chicken-and-egg scenario where audiences have to ponder how John could even send Kyle back in the first place if he hadn't yet been conceived by Reese.
While many fans have attempted to find a logical answer, Cameron was clearly encouraging audiences to simply accept the heady circuitousness of it all rather than try to find a clear solution.
The vast majority of popular time travel movies attempt to lay out a clear set of rules for audiences from the outset - think Back to the Future - but The Terminator totally flew in the face of any concrete logic, opting instead for brilliantly confusing cosmic poetry.
It's basically Cameron saying, "Time travel movies inherently make no sense. Accept the paradox. Think about it a little, but not too much."