This page contains a list of all hidden easter eggs and secrets within Borderlands.
Claptrap in Fyrestone MountainsUp in the mountains above the weapons shop in Fyrestone you will find this little guy waving at you.
- When a player is directly next to him - by grenade jumping or otherwise - the Claptrap will simply stand idle, frozen and not show any movement (save for his 'eye', and orb at the top of his antenna both glowing). Even if a second player were to go to the overlooking roof of the shops, the first player will still not see the Claptrap waving or jumping even though the second player will.
Hidden Vending Machine
This vending machine may have better and more powerful weapons that can be more expensive.
- For guests that join a game, sometimes the door will appear open but the machine is inoperable. At the same time, the door appears shut to the host.
Strange symbols adorn the debris that lie scattered across Pandora. These mysterious emblems contain hidden messages from travelers long since gone.Research found that the message reads "NICK WILSON HO OH". Nick Wilson is an artist who worked on the game.
The simple text translation of this QR code is
"Marcus Munitions, Inc.
- Unauthorized retailer of everything that goes BOOM!"
The mission where you deliver pizza to the "ninja turtles" there is a QR code on the pizza box with a familiar quote from the turtles.
Skrappy "All Grown Up"
Crazy Earl's pet skag Skrappy may have been cute and cuddly when you rescued him from those bandits a while back, but time has passed since then. Return to the scrapyard after defeating Baron Flynt and you will find that Skrappy isn't quite as cute and cuddly as you may remember.
T-Bone Junction Marcus' Shop
On the counter where Marcus is, there is a toy car. Inside it, is a little man. You can talk to him, his one line is "Hey, you seen my gun?".
Moxxi's shelfWhile in Moxxi's Red Light, if you look at the shelf above Moxxi there are many easter egg items. Among these are a miniature claptrap wearing a fake moustache, a Marcus bobblehead, a miniature of her announcing platform from the Underdome, and a pumpkin that flashes to the beat of the music. There is also a zombie brain that bleeds when shot and Hank Reiss's hat from The Zombie Island of Dr. Ned.
T-Bone Junction "Lilith Shrine"
Head to the area underneath the Junction, where Scooter asks you to find the Monster parts, and continue on towards the North, past the 'Rakk Hive rides' poster, you will find a building with a locked door. On the other side of this building is a chest and a red switch. Activate the switch, go back to the door and enter. Inside is a poster of Lilith, with modified spinning nipples on her breasts and a No.1 rosette. A Meat Popsicle of level at least 61 also appears in the refrigerator here.
There is a secret switch in Rust Commons East, if you glitch out of the map from Rust Commons West into Rust Commons East. This switch will complete the "North Ridge beacon activated" objective in the quest, "Relight The Beacons". 
Originally, the red chests of Borderlands were going to be well-hidden. This idea was thrown out, but one exceptionally well-hidden chest remains in Rust Commons West. It's got some good loot on the first playthrough, but has the loot of a standard red chest on the second playthrough. How To: Get to the Secret "Devs Chest"
After receiving the mission 'Another Piece Of The Puzzle', a blue hut in New Haven can be entered, which houses an elevator leading to a Hidden Basement containing The Rider. The hut cannot be entered after the quest is completed.
Rakkinishu will respawn in the north west area of Rust Commons West where it spawns for its mission. After killing Rakkinishu, it will again drop a shield called "Cracked Sash". The stats on the Cracked Sash are the same every time depending on which play through you are on. This item is from Diablo.
In the credits of Borderlands 1, a staff member writes, where you show graditude for family, friends... "Your Mom!"