Easter eggs in films originally gained prominence with the birth of the Internet, but they've really been there for years.
One could argue Alfred Hitchock popularised the idea, what with his consistent cameos in his films - even in Lifeboat, where he appeared on a newspaper - but the term 'Easter egg' reportedly began with The Rocky Horror Picture Show.
The story goes that the cast had an actual Easter egg hunt on the set and left three eggs in some of the sets, which people clocked when watching the film and thus came the term.
Here's seven of our favourite Easter eggs in film history.
7. WHERE EXACTLY IS VAL VERDE?
If you've seen Die Hard 2, Commando or Predator, then you've heard of this country - Val Verde. As it turns out, it doesn't exist and was completely invented by writer Steven E. DeSouza, who came up with it when he needed a tropical South American country. In Die Hard 2, Franco Nero - the villain of the film - was the military dictator of the country who was rescued by American mercenaries. In Predator, Arnold Schwarzenegger and his team were dropped into the jungles of Val Verde and in Commando, Arnold Schwarzenegger is blackmailed by another dictator of the country into assassinating its current leader.
6. WHY DOES A113 KEEP COMING UP IN PIXAR?
The phrase A-113 appears in every Pixar film. Literally every single Pixar film. But what does it mean? As it turns out, A-113 refers to the the first year graphic design studio in the California Institute of Arts where John Lasseter and Brad Bird studied.
5. THE 'X' IN THE DEPARTED
If you go back and watch The Departed, you might keep seeing an X-shape appear near certain characters. This was a deliberate reference by Martin Scorsese, which called back to old gangster epics in the '30s. Whenever a character was due to be killed, it would be foreshadowed by some kind of an 'X' hanging over them. In The Departed, it was either the 'X' on a window from masking tape, some kind of structure in an airport, or even the carpets.
4. THERE'S A STARBUCKS CUP IN EVERY SCENE IN FIGHT CLUB
This was originally propagated by David Fincher and it's hard to verify, but it looks as though it's correct. In every single shot of Fight Club, there's a Starbucks reference - either a cup of coffee or the logo itself. Snopes has never been able to spot every single one, but Fincher is adamant that they're there.
3. JOHN CARPENTER'S THE THING COULD HAVE BEEN OVER IF ANYONE UNDERSTOOD NORWEGIAN
At the very beginning of John Carpenter's The Thing, a Norwegian sniper is hunting a Husky which is actually the alien creature. When it reaches the base where Kurt Russell et al are hanging out, he runs up to it and starts shouting at them in Norwegian. Of course, nobody in the audience knows what he's saying and neither do the characters on screen. As it turns out, he's actually shouting about how the dog is an alien and not to let it touch them.
2. THE RATHARS IN THE FORCE AWAKENS ARE TAKEN FROM RAIDERS OF THE LOST ARK
JJ Abrams is no stranger to references in his films, and pretty much all of his films are loaded with them. One noticeable one that may have escaped everyone's attention is one he snuck in The Force Awakens. The Rathars - the weird creatures that Han and Chewie were transporting - have the exact same sound effect as the boulder from the opening scene of Raiders Of The Lost Ark. The sound editor actually pulled the sound effect from Skywalker Sound's library and threw it in.
1. WHERE'S WALLY IS IN APOCALYPTO
Yes, really. It's literally one frame in twenty-four frames per second, but it's there. In the scene where Jaguar Paw falls into a crater filled with dead bodies, there's a split-second frame of Wally - from Where's Wally - lying on top of the bodies. Nobody's really sure why it's there, but it's likely Mel Gibson threw it in to jar people's vision and freak them out.