[SPOILERS] 6 details you might have missed on the 'Game of Thrones' season 7 premiere episode

Warning: Spoilers ahead for this week’s episode of “Game of Thrones” season seven, including speculation of future events.

“Game of Thrones” season seven kicked off with an epic cold-open that surely had fans fist-pumping around the world. Between Arya’s reverse-Red Wedding murders, Daenerys’ arrival to Dragonstone, and more Tormund/Brienne eyebrow raising, there were several significant moments you may not have caught.

Let’s dive into the most important details you might have missed.

The Valyrian steel blade used in Bran's assassination attempt on season one cropped up in one of Sam's stolen Citadel books.

The blade as seen in Sam's book, and the blade on season one.

Sam stole several books from the Citadel library's restricted section, and while he was flipping through the pages we got a peek at a drawing of a very important weapon.

The dagger is often referred to as the 'catspaw blade' -- a reference to the would-be killer (or catspaw) who tried to kill Bran on season one. We knew the blade was made from Valyrian steel and had a hilt made of 'dragonbone,' but its origins have been a big mystery in the books and the show.

Based on Sam's book, it looks like we now know the blade is an ancient Targaryen weapon.

So who has the blade in the show now?

The dagger was last seen on Ned's desk in season one, episode four.

In the books, Littlefinger took the blade from Ned Stark when he betrayed him. But in the show, it's a bit of a mystery -- one that could involve Arya Stark. Odds are very high that Littlefinger has the blade on the show, too, but we can't be too sure.

Ed Sheeran's cameo featured more than just a lovely song -- the ballad had a huge significance in the book series.

The lyrics for 'Hands of Gold' are very important.

In the books, Tyrion keeps his lover Shae in a house in King's Landing (not inside the Red Keep as Sansa's handmaid). This meant Tyrion would travel from the keep to her manse. A singer named Symon Silver Tongue befriended Shae, and tried to blackmail Tyrion into helping him sing at the royal wedding -- or else he'd sing a song about Tyrion and Shae for all the world to hear.

Here are the song lyrics, written about Tyrion and Shae:

He rode through the streets of the city,

Down from his hill on high,

O'er the wynds and the steps and the cobbles,

He rode to a woman's sigh.

For she was his secret treasure,

She was his shame and bliss.

And a chain and a keep are nothing,

Compared to a woman's kiss

For hands of gold are always cold

But a woman's hands are warm

The 'hands of gold' refer to Tyrion's chain he wore as Hand of the King -- the same chain he uses to kill Shae in the books.

Tyrion wore a chain made from golden hands in 'Blackwater,' but didn't use this same jewellery to kill Shae on the show.

In the books, Tyrion (and whoever is Hand of the King) wore a gold chain made from linked hands. He used that chain to murder Shae, and said 'for hands of gold are always cold' as he killed her.

The show changed up this scene slightly, since Symon Silver Tongue's song wasn't a part of the series -- until now. Ed Sheeran's cameo was a good opportunity to give book readers a hat tip.

Sandor Clegane's grave digging scene was yet another nod to book readers, and it has to do with the most hyped theory of all time.

Helen Sloan/HBO
This was a tender moment, but some fans were getting hyped.

Sandor 'The Hound' Clegane was left for dead in both the books and on the show. Many people began theorizing about ways in which The Hound might return, and one such theory was referred to as 'Gravedigger.'

In the books, Brienne of Tarth visits a monastery and speaks to the Elder Brother who claims to have found The Hound and laid him to rest. But Brienne spots a huge man (around The Hound's height) digging graves, and notices that The Hound's horse is being kept in the stables nearby.

You can read the full theory here, but the point is that many believed Sandor Clegane was just disguising himself as a gravedigger in this monastery.

The gravedigger theory then spawned a second, more extreme theory called Cleganebowl.

Skye Gould/Tech Insider

Cleganebowl postulates that Sandor and Gregor Clegane (The Hound and The Mountain) will fight to the death in an epic trial-by-combat. 'Game of Thrones' showrunners David Benioff and D.B. Weiss seem to be aware of this theory, because they have made allusions to it in the past through their writing.

Having The Hound literally digging a grave in the opening episode of season seven feels like one more not-so-sly reference to the fight of the ages fans are dying to see.

The Night King is literally bringing a storm with him.

Plus the giant wight was terrifying.

On the season six finale, Jon Snow addressed the northern lords who wanted to hole up in their castles and wait out the coming winter. 'The true enemy won't wait out the storm,' Jon said. 'He brings the storm.'

Turns out Jon meant that literally -- the Night King was seen on the season seven premiere walking ahead of a huge moving snow storm, with hundred of wights walking behind him.

Fans have long wondered if the White Walkers are simply more adapted to cold, and will therefore turn up when its coldest outside, or are they actually causing the extreme cold? Now we have our answer.

Euron's 'gift' for Cersei will likely be rejected, given the episode three synopsis.

Euron is meant to be this season's big bad guy.

When Cersei refused Euron's flippant marriage proposal, he said: 'You need proof of my honest intentions. In my experience, the surest way to woman's heart is with a gift -- a priceless gift. I won't return to King's Landing until I have that for you.'

HBO released the description for episode three, 'The Queen's Justice,' ahead of the premiere. The third line says 'Cersei returns a gift.'

This is likely the same gift Euron just promised her. Speaking of, what will the gift be? Another ally? The head of an enemy? We'll have to wait for episode two to find out.

The last tiny detail was in the opening credits. We got a new city added! The Citadel in Oldtown was prominently featured.

The towering Citadel in the opening credits.

The opening credits featured a cool Easter egg last season, too. The sigil atop Winterfell was the flayed man of House Bolton for nearly two seasons, and then it finally showed the direwolf of House Stark in the season six finale.

So it was really awesome to see Oldtown added to the list of beautifully rendered cities in the opening sequence. Perhaps more Easter eggs will come later in the season.

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