The art of foreshadowing is a delicate one, whereby filmmakers subtly hint at things to come, ranging from moments of mild significance to major, game-changing reveals.
When foreshadowing is done well it can prove tremendously rewarding for repeat viewers, effectively winking at them for bothering to watch the film again and nodding towards future plot developments.
Foreshadowing isn't always subtle, but sometimes filmmakers are meticulous enough to include brilliantly sneaky hints at what's to come that only the most attentive and eagle-eyed of audience members will have a hope of catching.
These 10 films, all thoroughly entertaining and many of them even outright classics, all dared to include the sneakiest, subtlety hints at massive spoilers, such that anyone who noticed them on a subsequent viewing would surely start pointing at the screen like Leonardo DiCaprio.
But don't feel bad if you missed any or even all of these feats of foreshadowing, because they're so ingeniously hidden in the frame that the overwhelming majority of people would simply never notice them.
In each case, they're inarguable proof that the filmmakers involved put a lot of thought into how their films were constructed...
10. Sam Rockwell's Name Appears Twice In The Opening Credits (Because He's A Clone) - Moon
Duncan Jones' terrific 2009 sci-fi film Moon centers around Sam Bell (Sam Rockwell), a man nearing the end of a three-year mining job on the far side of the Moon.
Eventually it's revealed that Sam is actually one of many clones of the original Sam Bell, a fact that's subtly and ingeniously nodded at in the film's fantastic opening titles sequence.
The credits are displayed on screen while we see Sam running on a treadmill, but if you look closely, you might notice that the text often appears twice, either as a shadow or reflection, in the environment.
This is especially noticeable when Sam Rockwell's own credit appears, with a smaller version also visible to the left-hand side of the frame.
This was clearly an artistic choice intended to slyly nod at the film's chief conceit centered around doubles and clones.
That the clones also have a fixed three-year lifespan is even symbolised by the shadows and reflections being less-refined than the upfront text - quite literally, pale imitations.
Hell, the film's poster even hints at the twist, what with Rockwell's name "echoing" numerous times in gradually degrading detail, hinting at the clone reveal.