“Game of Thrones” is known for its attention to detail, so it should come as no surprise that the show sometimes includes a few Easter eggs, the term given to the subtle or obscure references writers occasionally include in the scripts that usually only obsessive fans can detect.

In “Game of Thrones” Season 4, the show’s linguist slipped in a hidden “Monty Python” joke that is one of several of this season's Easter eggs.

Famous Swords In The Iron Throne

The centerpiece of King's Landing and what many characters are fighting for, the Iron Throne has its share of secrets. In "A Song of Ice and Fire," the Iron Throne was made out of the melted down swords of Aegon the Conqueror's enemies. With such a large prop, it's only fitting that the "Game of Thrones" crew was able to sneak a few famous swords in the Iron Throne.

Reddit user NoMoreHodoring pointed out Glamdring, Gandolf's sword from "Lord of the Rings," could be found in the center of the Iron Throne. Another Reddit user noted that the sword to the right of Gandalf's was the sword of Robin of Locksley. Another sword from "Kingdom of Heaven," directed by Ridley Scott and starring Orlando Bloom, also makes an appearance in the Iron Throne, according to HitFix

George W. Bush's Head On A Spike From "Game of Thrones" Season 1

After HBO released "Game of Thrones" Season 1 on DVD, series creators David Benioff and D.B. Weiss spoke on the director's commentary track about how they used whatever prop heads were available at the studio during several beheading scenes. One of those heads just so happened to be in the image of former President George W. Bush. According to io9, Bush's head could originally be seen in "Game of Thrones" Season 1, episode 10, "Fire and Blood," as Joffrey shows Sansa the head of her father, Ned Stark, which is mounted on a spike. In the episode commentary, the creators said, "The last head on the left is George Bush. 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." After the controversy faded, HBO, Benioff and Weiss apologized for using Bush's head as a prop and changed the scene so the former president's head is no longer recognizable on the DVD box set.

Very Obscure Fantasy References

"Game of Thrones" is a fantasy series at heart and it contains a few references that may have only caught the attention of the show's most diehard fans. In  Season 1, episode 4, "Cripples, Bastards and Broken Things," Viserys is discussing famous dragons and makes a reference to Vermithrax, the main villain of 1981's "Dragonslayer," notes Badass Digest. Devin Faraci also noted that "Game of Thrones" Season 4 features a reference to Stombringer, a famous sword found in several novels written by Michael Moorcock, which is wielded by Elric of Mlnibone. 

The "Monty Python" Joke From "Game of Thrones" Season 4

Season 4 features the biggest "Game of Thrones" Easter egg to date. While many "GoT" secrets are carefully hidden or are very brief, the show's linguist slipped in a whole Monty Python gag. David Peterson discussed the joke in an interview on the "Making of 'Game of Thrones'" blog.

In "Game of Thrones" Season 4, episode 3, "Breaker of Chains," the Meereenese champion shouts something at Daenerys, and Missandei doesn't do a great job translating the challenge. Peterson responds, "Nathalie Emmanuel [Missandei] is translating -- but she's not translating what he's saying. He's actually saying a Low Valyrian translation of the French guy's insults in 'Monty Python and the Holy Grail.' That was [series creator] Dan Weiss's idea, and it was so hilarious that I had to do it." In fact, the Meereenese champion starts off by saying "Your mother is a hamster." Peterson also provides a handy High Valyrian guide for several popular "Game of Thrones" quotes including "You know nothing Jon Snow."

Of course, these are just the "Game of Thrones" Easter eggs that have been discovered by fans, and there may still be more hidden throughout the series' first four seasons. Considering the amount of detail in the series -- for example, take a look at the costumes and the props from Season 4 -- chances are there are a few more "GoT" secrets yet to be unearthed.

Some bonus "Game of Thrones Trivia:

Many "Game of Thrones" actors have appeared in the "Harry Potter" franchise, nine in all, including Natalia Tena (Osha) who played Nymphadora Tonks and David Bradley (Lord Walder Frey), who played Argus Filch. "Game of Thrones" also features actors who appeared in several British television series, including "Doctor Who," "Downton Abbey," "Skins" and "Misfits." Iain Glenn (Jorah Mormont) has appeared in both "Downton Abbey" and "Doctor Who."