In Vilemyr Inn, Ivarstead, you'll find a woman by the name of Temba Wide-Arm. Her name is a subtle reference to the Star Trek: The Next Generation episode 'Darkmok', in which Picard and his crew encounter a race of aliens called the 'Tamaraians'. At one point, Picard is stuck on a planet's surface. He attempts to make a fire, but fails. A Tamarian named Dathon takes a branch from his own fire and throws it to Picard, saying "Temba, his arms wide", to make it clear the fire was a gift.

During the quest "Proving Honor", if the Dragonborn asks Farkas if the companions are werewolves, he ends his response with "It's a secret to everybody." This is a reference to The Legend of Zelda series, where this phrase is infamously repeated.

Directly south of Markarth, near Purewater Run, there is a stone bridge near a waterfall. If it's your first time there, you'll see two goats walking on the bridge, and then a third one climbing up from under the bridge to join them. If you go under the bridge you can find a dead troll. This scenario is a reference to the Norwegian fairy tale "Three Billy Goats Gruff".

When near Sheogorath, he will sometimes say "Do you mind? I'm doing the fishstick. It's a delicate state of mind." This is a reference to the Fishy Stick meme which began on Bethesda's Official Forums and went on to become a running gag in Elder Scrolls games.

When Athis is asked why he joined the Companions, his response is "Fortune and glory, friend. Fortune and glory." This is a reference to a very similar line from Indiana Jones and the Temple of Doom.

During the night, you may encounter a Headless Horseman, a reference to Washington Irving's "The Legend of Sleepy Hollow".

The guards in Skyrim will more often than not say "Let me guess, somebody stole your sweetroll" to the player, this is a gag that Bethesda Softworks have been running since the very first Elder Scrolls game.

It's possible that the popular phrase, "I used to be an adventurer like you, until I took an arrow in the knee" was put into the game because Skyrim was the first Elder Scrolls game to not include greaves (knee armor).

The Dragonborn DLC contains a reference to Morrowind in which a Wizard casts a spell attempting to fly but winds up ultimately falling to his death.

Slightly Northeast of Bleakwind Basin, there is a pond with a skeletal arm holding a leveled sword, which is a reference to the Lady in the Lake in the legend of King Arthur.

In Endon's House in Markarth, there is a shelf in the back of the room with Sliced Goat Cheese, a row of Garlic, and some Glow Dust arranged to look like a scene from Pac-Man.

At the very top of the Throat of the World, there is a special pickaxe that the player can obtain. The name of this pickaxe is 'Notched pickaxe', and is thought to be a reference to Minecraft creator Notch.

Southwest of Winterhold, in Bleakcoast Cave, there is a part of the cave guarded by frost trolls where you will find parts of a skeleton hanging from the icy ceiling. On the ground below it is a Steel Greatsword of Weariness. This is a reference to Star Wars: The Empire Strikes Back in which there is a scene where Luke Skywalker is stuck to the ceiling of an icy wampa cave and must use the Force to retrieve his lightsaber to cut himself free.

In the Heroic Fantasy book 'The Name of The Wind' by Patrick Rothfuss, the main character Kvothe stumbles at one point (Page 22 in the attached PDF) and says "I took an arrow in the knee on my way through the Eld three summers ago" The book was published in 2007 and might be where Bethesda got the line from. If this is the case, then 'arrow in the knee' may be an Easter egg or reference to the novel.

In the games files there is an unused Pit or Arena Called "Windhelm Pit Entrance". Entering the Pit spawns 2 Argonians (Both Male), Nords, Dark Elves and Imperials NPCs, They are all called 'Pit Fans', who are supposed to be spectators. It is believed that Windhelm was going to have an arena at some point of development where you would face against animals or NPC Bandits. There are also Pit guards who are fully voiced, but they cannot be viewed during normal gameplay. The place can be viewed by entering the console commands "coc WindhelmPitEntrance" and "coc WindhelmPitExterior".

The DLC Expansion for Skyrim, "Dragonborn", contains many of the music tracks that were previously found in The Elder Scrolls III: Morrowind. This is fitting, seeing as the game is set on the island of Solstheim, in close proximity to the Morrowind region of Tamriel.

Jonah Lobe, one of the 3D artists for the game, modeled the in-game giants after his father Jim Lobe.

Mannequins are meant to be stationary objects that display armor inside houses. Supposedly, they are programmed as NPCs with a simple script designed to make them stand still whenever they are in the player's presence. However, when a building with a mannequin inside is loaded, if the mannequin's script isn't loaded fast enough they will walk around and act like normal NPCs for a short time, a glitch that causes occasional instances of mannequins spawning away from their pedestals, or just acting like they are alive before becoming stationary again.

Within the game's files is an unused NPC named "College Guard". They would have acted similarly to Hold Guards, but for The College of Winterhold.

There is an unused model for the "The Ring of Khajiiti", a Daedric artifact associated with both Meridia and Mephala. However, it goes unused as both Daedric Princes reward different items. The Ring of Khajiiti was present in The Elder Scrolls IV: Oblivion, so the developers may have intended for it to return.