George R. R. Martin's A Song of Ice and Fire book series and the HBO TV adaptation Game of Thrones are known for their passionate fan bases—but there are so many subtle references, in-jokes, and moments of foreshadowing hidden throughout both that even the most obsessive fans can't possibly catch 'em all. 

1. A Diminished Iron Throne

The Iron Throne has become one of the series' most recognizable images, but the Iron Throne used in the show is much smaller than the one George R.R. Martin envisioned. The show makes a sly reference to this when Varys says that it's "[a] thousand blades, taken from the hands of Aegon's fallen enemies. Forged in the fiery breath of Balerion the Dread," to which Littlefinger replies, "There aren't a thousand blades. There aren't even two hundred. I've counted."

2. Famous Swords

Speaking of the Iron Throne, several redditors have spotted some famous swords welded into the chair—including Orlando Bloom’s sword from the film Kingdom of Heaven and Gandalf’s sword, Glamdring, from The Lord of the Rings series.

3. The 43rd U.S. President

The show is notorious for repurposing props, and in a blink-and-you-miss-it moment from season one, episode 10, you can see George W. Bush’s head on a pike in King’s Landing. Show runners David Benioff and D.B. Weiss explained this in their DVD commentary: "George Bush's head appears in a couple of beheading scenes. It's not a choice, it's not a political statement. We just had to use whatever head we had around." Despite their insistence that they didn't mean anything by it, HBO wasn't pleased, saying in a statement, "We were deeply dismayed to see this and find it unacceptable, disrespectful and in very bad taste. We made this clear to the executive producers of the series who apologized immediately for this inadvertent, careless mistake. We are sorry this happened and will have it removed from any future DVD production."

4. Tyrion's Nose

After the Battle of Blackwater Bay, Cersei tells Tyrion that she has heard rumors that his nose had been cut off. In the books, Tyrion actually does lose his nose in the battle, but this was changed because of shooting restrictions. “It would cost a lot of money, because they’d have to put a little green sock on my nose,” Dinklage told Entertainment Weekly. “Every scene I was in they’d have to [digitally paint] over my face in every frame and that’s costly and time consuming. I think a scar solves everything.”

5. Jaime's Hand

In season three's "The Bear And The Maiden Fair"—that's the one in which Jaime Lannister returns to Harrenhal to save Brienne—Locke tells Jaime to “go buy yourself a golden hand and f*** yourself with it.” This is a direct reference to the golden prosthetic hand that Jaime would later receive in season four.

6. The Deaths of Joffrey, Shae, and Tywin

In season four’s "The Mountain And The Viper," Littlefinger tells stepson Robin Arryn that “People die at their dinner tables. They die in their beds. They die squatting over their chamber pots. Everybody dies sooner or later.” These words clearly foreshadow the deaths of Joffrey, Shae, and Tywin, who died at a dinner table, in a bed, and on the toilet, respectively.

7. Monty Python

Season four contains one of the show’s most extensive private jokes. In episode three, “Breaker of Chains,” the Meereenese fighter shouts an insult in Low Valyrian. According to the show’s linguist, David Peterson, the rider was actually shouting, “Your mother is a hamster and your father smells of elderberries,” a reference to Monty Python and The Holy Grail.

8. Destiny

Earlier in season five, one redditor noticed that Tyrion was sitting in front of a window that bore a striking resemblance to actor Peter Dinklage's Ghost from the video game Destiny.

9. R+L=J

R+L=J is a popular Game of Thrones fan theory that states that Jon Snow is not Ned Stark's son, but is in fact the son of Rhaegar Targaryen and Ned's sister Lyanna. Early on in season one, the show acknowledges the theory by showing the letters "R L" carved into the wall right next to Jon.

10. Rocker Cameos

Musical guests are starting to become a trend on Game of Thrones. During season three's infamous Red Wedding, Coldplay drummer Will Champion is featured as one of the musicians playing the "Rains of Castamere." Later, in season four's "Purple Wedding," Icelandic band Sigur Ros again perform the "Rains of Castamere" before they are pelted with coins by King Joffrey. This season featured three members of the band Mastodon playing Wildings in "Hardhome."

11. The New York Giants

Martin is a big football fan and will sometimes slip references to the New York Giants into his books. In A Dance With Dragons, he writes, “The galley was also where the ship's books were kept ... the fourth and final volume of The Life of the Triarch Belicho, a famous Volantene patriot whose unbroken succession of conquests and triumphs ended rather abruptly when he was eaten by giants.” This is clearly a reference to the New York Giants' Super Bowl victory over the previously undefeated New England Patriots. 

In addition, the giant Wun Wun gets his name from former Giants quarterback Phil Simms, who was number "11."

12. The Three Stooges

The books also contain a reference to The Three Stooges. In the first book, A Game of Thrones, Catelyn arrests Tyrion with the help of three knights from House Bracken: Lharys, Mohor, and Kurleket, a Westerosi spin on Larry, Moe, and Curly.

13. The Grateful Dead

At an event at the 92Y, Martin confirmed the influence of the band's music on his books: "I'm certainly a fan of the Grateful Dead. My wife Paris is perhaps more of a fan of the Grateful Dead than I am," he said. "I have Grateful Dead lyrics rattling around in my head all the time. 'Ripple' is one of my favorite songs of all time... 'There is a road, no simple highway.'" The Weirwood trees are even named for Bob Weir, the band's co-founder and guitarist.