Though not an exact replica, the .45 auto submachine gun in the Honest Hearts DLC is based off of the Thompson submachine gun.

It is said by Joshua Graham in the Honest Hearts DLC that the .45 Auto pistol is based on a nearly 400-year-old design from one of his Mormon ancestors and is the trademark weapon of the New Canaanite tribe. This alludes to the creator of the real-life pistol this gun is based on, the M1911, created by John Moses Browning. Like the New Canaanites, Browning was a member of the Mormon church from Utah.

Most of the Honest Hearts Tribals speak a creole language.

The Dead Horses' language is based on German, English, and Navajo, although the morphology of the Navajo is unrecognizable.

The White Legs speak a combination of languages from tourists and locals in a place called Res.

The Sorrows language seems to be a combination of broken English, German, Spanish, and hints of Japanese.

With the Wild Wasteland perk activated, players can find the words "Romanes eunt domus" written on the side of a building in Cottonwood Cove. This is a reference to the Monty Python movie, "Life of Brian", in which Brian attempts to graffiti "Romans go home" on a building in Latin. However, the statement has several translation errors (much to the chagrin of a passing centurion) and literally translates to "People called Romanes they go the house."

The perk "In Shining Armor" doesn't actually do anything. The perk was supposed to give the player an additional +5 Damage Threshold against energy weapons while wearing any metal armor, and +2 while wearing reflective eyewear.

The perk doesn't provide any Damage Threshold boost due to the fact that the parameter that is referenced when checking the skill type of enemy weapons is "Energy" instead of "EnergyWeapons". This means that the function "IsWeaponSkillType" will never return a value that can activate the perk effect, because there is no weapon skill called "Energy".

The challenge "A Slave Obeys" requires the player to Spoiler:kill Mr. House with the 9 Iron or Nephi's Golf Driver. This is a reference to the original Bioshock, in which the player Spoiler:beats the game's main antagonist, Andrew Ryan, to death with a 9 iron while he repeats the words "A man chooses, a slave obeys."

The Child at Heart perk from Fallout 3 was set to return to New Vegas, but was ultimately cut, most likely because there are very few children in the game. Unused dialogue can still be found within the game's audio files, however.

A portrait of the mother and father of Fallout 3's protagonist, The Lone Wanderer, can be found in Vault 21, next to Sarah's bed.

If the player chooses to arm Archimedes I and leave Fantastic alive, in the quest "That Lucky Old Sun", upon returning the player will find Fantastic wearing Legion armor and having just killed his co-worker, Ignacio Rivas, stating "Hey man, when in Rome."

In the "Dead Money" DLC, when entering the wine cellar near the bell tower from which the player triggers the Gala Event, the phrase "I AM NOT YOUR MUMMY" is scrawled on the central pillar. This is in reference to the Ghosts' gas masks and the two-part episode of Doctor Who, "The Empty Child and The Doctor Dances".

If the player has the Wild Wasteland trait, and nukes both the NCR and Caesar's Legion at the end of the Lonesome Road DLC, the ending slide will Spoiler:quote Charlton Heston and show a picture representing the ending scene from the original Planet of the Apes.

A Wrecked Highwayman can be found half-submerged in mud and, upon finding it, one of two background songs from Fallout 2 ("My Chrysalis Highwayman" or "Gold Slouch") will play. The trunk is filled with Energy ammunition, making it a nod towards the Highwayman in Fallout 2, which used Energy ammo as a fuel source. The original idea for this encounter came from J.E. Sawyer, who originally planned it for the cancelled Van Buren game, which would have included the Tanker FOB in the trunk from Fallout 2.

Matthew Perry was cast in Fallout: New Vegas due to being a fan of the previous game; Fallout 3. He also gave away a signed copy of Fallout 3, not because he was in it, but rather just because he claimed it was his favorite game.

When playing as a character with low intelligence and speaking to the vagrant in Freeside while doing the quest "I Can Make You Care", using intelligence to inquire about weapons and other precious loot will cause him to speak clearly and intelligently, and to caution the player to avoid his current predicament.

This seems to be a reference to Torr from Fallout 2 who has a similar string of interactions with low intelligence players.

Despite a higher resolution texture being available in the game's resources, the Spiked Knuckles used by the player do not use the high resolution texture.

A Vault Boy image named "perk_survivalist" appears in the game files. It differs in appearance from the original survivalist perk (found in Fallout, Fallout 2, and Fallout Tactics), and its unclear what it would do as it was never implemented into the game though it seems to imply that the perk was originally planned to appear in New Vegas.

Dennis Crocker was originally planned to be Caucasian, but his lines were voiced by a non-Caucasian voice actor so the developers changed the character's appearance accordingly.
His original design can still be seen on the collectors edition playing cards.

The Mr. New Vegas radio show has unused news reports detailing the outcomes of each game ending, which cannot be witnessed as the game doesn't allow you to play past the ending due to the drastic differences the game world would experience based on the outcome.

As a unique pre-order bonus at K-Mart, buyers received four coasters representing the four major casino found in the game, The Ultra-Luxe, Vault 21, The Tops, and the Lucky 38.

By using console commands during the ending slideshow it's possible to find a character called "Ron the Narrator", who is used to narrate the slides and other sections of the game.

He can be seen wearing Legion armour, and is based off the actual narrator, Ron Perlman.