Hollywood filmmakers like to keep their cards close to their chests, only revealing stills and footage from their blockbusters-in-the-making when they're good and ready.
But sometimes they don't get a say on that because, in a world where most people's phones have a half-decent camera attached, set leaks are more of a thing than ever.
This a problem that no doubt dates back to the early days of film journalism, but it's taken on a new level of prevalence since every man and his dog gained access to the internet and set up social media accounts.
Most directors and movie studios loath set leaks for obvious reasons - although there's evidence to suggest they're occasionally behind them - but some fans scour the web for this content and treat it with as much reverence as a Super Bowl trailer.
The leaks which typically make waves come from the set of the biggest blockbusters, and none of Hollywood's most prestigious franchises appear to be a water-tight ship, with the likes of Star Wars and the Marvel Cinematic Universe having their secrets spilled.
If you enjoy these inside scoops, the good news is that they continue to flood in...
10. Boba Fett Might Be In The Han Solo Movie
Here's an example of a set spoiler that was outed by the director himself.
Ron Howard has been tweeting from the set of his upcoming young Han Solo movie and the filmmaker may have revealed more than he intended to.
Hawk-eyed fans have spotted a familiar-looking silhouette in the background of one of his photos, and the internet has lost its collective mind over the idea that this is Boba Fett, Star Wars enthusiasts' all-tie favourite bounty hunter.
The upper portion of the shadow in question does appear to be the right shape to pass for Boba's trademark helmet but, on the other hand, it could just be a regular old Stormtrooper... or a lamp.