Tiny Tina's Assault on Dragon Keep contains a reference to the YouTube user "Bro Team Pill". At the end of the optional mission "My Dead Brother", one of the mission completion messages reads "Bro Team Kill".

The side mission "Rocko's Modern Strife" is a reference to the show Rocko's Modern Life.

The sidequest, "Too Close for Missiles", contains a large number of reference to the film "Top Gun". The quest starts after talking to Loggins (a reference to Kenny Loggins, the writer of the song "Danger Zone" from the film's soundtrack) outside of Ellie's garage. During the mission, Loggins will repeatedly call the player "Goose", in reference to Maverick's wingman. The mission involves gathering volleyballs and gasoline to light a volleyball net on fire. Following that, 3 NPCs known as Shirtless Men spawn and attack the player. All of the objectives reference the infamous sand volleyball scene from the film. Loggins himself also says "Danger zone" multiple times during the quest.

The inside cover artwork for the game was based on artist Olly Moss's art style of his homages to various franchises, however, the clouds in the artwork were taken directly from one of Moss's own pieces; from his Star Wars: The Empire Strikes Back fan poster.

When Moss found out, he took to Twitter to express his disappointment, however, Gearbox CEO, Randy Pitchford, soon contacted him and apologized for the incident.

Handsome Jack had dialogue recorded for the New-U Station revival taunts, but they were unused in the final release.

The side quest "Raiders of the Last Boss" in the Tiny Tina's Assault on Dragon Keep DLC is a clear reference to the Indiana Jones movie "Raiders of the Lost Ark."

The optional mission in Sir Hammerlock's Big Game Hunt, "Still Just a Borok in a Cage", is a reference to The Smashing Pumpkins song, "Bullet With Butterfly Wings." More specifically it's a reference to lyrics for the chorus, "Despite all my rage, I am still just a rat in a cage."

The Baby Maker SMG explodes into two smaller versions of itself when reloaded. The chances of spawning a pink or blue variation are actually based on US birth statistics for females and males.

During a second playthrough on "True Vault Hunter Mode", after the chapter "Where Angels Fear to Tread", the player can go to Claptraps Place and find an event item in the fireplace called "Geary's Unbreakable Gear" with the description "Only a brisk walk to Eridium Blight will reward the courier". The player must then travel to Mount Hellsfont, located in the northwest corner of Eridium Blight without dying, using a fast-travel station, or riding in a vehicle spawned from a "Catch-A-Ride" station. If the player is successful, they'll encounter a special enemy named Geary. If the player lets Geary attack them, he'll steal the gear and jump into the lava. This will cause three Rakks to appear and drop three loot chests, one of which will have purple gear. This is a reference to "The Lord of the Rings" book trilogy by J.R.R Tolkien, and the journey to Mount Doom.

Spoiler:After Mordecai shoots Bloodwing with a tranquilizer dart at the end of her boss fight, it is possible to shoot her after she falls to the ground. Even though she is defeated, every shot fired at her head will still count as critical hits in your Badass Ranks.

The Bane's vocal effects will still play even after lowering all of the game's volume settings.

Torgue vending machines in the Campaign of Carnage DLC all have 80085 typed into the selection box, an obvious reference to the juvenile joke of spelling the word "BOOBS" out on a calculator.

In Frostburn Canyon, an error message can be found on a monitor with a humorous message stating that the user has damaged their computer due to viewing pornography.

The full message reads:

The side quest "3:10 to Kaboom" is a reference to the movie 3:10 To Yuma.

In Borderlands 2, There's a character named Michael Mamaril that will give the player free (and usually rare) loot. This character is based on a real-life person who died at the age of 22. His friend wrote to Gearbox, the game's developers, asking them to do a eulogy using the voice of the fan-favorite character "Claptrap". Gearbox not only fulfilled his request, but also added Michael as a character in Borderlands 2, so he could live on forever in Borderlands.

There are a number of QR codes scattered around Pandora. Scanning these codes using a QR code scanner will result in different messages.

Pizza Boxes: "Wise man say, forgiveness is divine but never pay full price for late pizza. -Captain Picard."
Possibly a reference to 4chan, where many pictures of famous characters are misquoted. In this case, a Michelangelo quote from Teenage Mutant Ninja Turtles and Captain Picard from Star Trek: The Next Generation.

In Zed's Pharmacy: "Thank you so much for playing our game, now I'm rich with love AND money! !!Nick Wilson!! Ditto!!!"
A reference to the artist Nicholas W., an artist at Gearbox.

Various Places: "NICK WILSON/ /HO OH"
Same as the previous message, a reference to Nicholas Wilson.

The targets of the mission "Splinter Group" are four mutated raiders named Mick, Lee, Ralph, and Dan. This is a play off of the Teenage Mutant Ninja Turtles named Michelangelo, Leonardo, Raphael, and Donatello. The other similarities include their hideout being in the sewers, their name "Splinter Group" after the rat master "Splinter", their surfer-like language ("dude", "brah") and their craving for pizza used to lure them out.

There is a small tent located in the Highlands. Entering the tent triggers a double rainbow to appear on the horizon, with a sound clip from either Handsome Jack or Claptrap imitating the Double Rainbow Youtube video.

In The Fridge, there is a quest related enemy named Laney White, accompanied by 7 midgets, each named with a foul adjective. This is likely a play off of Snow White and the 7 Dwarves, further implied by the related achievements, "Fairest of Them All", and "It's Off to Hell We Go".

In the Caustic Caverns is a cave with a number of pixelated blocks. These look very similar to blocks from Minecraft, which break when punched a number of times. Behind these blocks are a handful of enemies called Creepers, including a Badass Creeper, a kind of enemy also found in Minecraft. Among the loot they drop when killed is a new head skin with a pixelated look.