Tuco's grill can be found on a shelf in Sheriff Black's office. This is a reference to Hank keeping the grill as a trophy. This is likely because RAGE had been featured on the show; Jesse Pinkman can be seen playing the game on several occasions, albeit (incorrectly) with a light gun.
It should be noted that the actor that voices Gabe, Matt Jones, also plays a character named Badger on Breaking Bad.
Charon is the name of the character who brings the protagonist back and forth from Subway Town and Wellspring. In Greek mythology, Charon is the ferry man who brought souls of the departed back and to Hades across the river Styx.
When upgraded with its heaviest armor, the Monarch resembles the "Monster", an armor-plated race car driven by Jason Statham in the 2008 movie Death Race. As well as general design, the cars both feature a similar red and black paint scheme.
Note that an autograph from "Cacodemon" can be found among the various graffiti within this room. This is referencing the Cacodemon monster from the Doom series.
While having the Rocket Launcher equipped and standing in one spot doing absolutely nothing for about five minutes, the targeting screen will flip down and a game of Doom will be playing.
The small object called "Black Coffee Mug" is emblazoned with a Doom 3 logo. The cups can be found throughout the Wasteland. For example, one could be seen on the Mayor Clayton's desk in Wellspring.
There is the secret Doom room in RAGE that is located in the Gearhead Vault. Follow the steps here to find it.
On the upper-left corner of the Doom door "E1M1" is written which is the internal label for "Hanger", the first level of Doom.
Several boxes in the game are labelled "MIXOM: Model A-2515", e.g. in Wellspring, next to Rusty. A Mixom building is seen when near the Dead City. There are quite a few barrels found in different places labeled "Mixom". It also says MIXOM on the side of the gas tanks on the default buggy. Mixom was a tool company in Doom 3 that was constantly confused with its rival, Moxim.
In Subway Town, an elderly drug enthusiast named Siri can be seen smoking a hookah. On this hookah there is part of the cover art from Doom II.
Up at Crazy Joe's Swamp, Crazy Joe himself has a Doom 3 shirt on.
In Subway town, there is a WANTED vid screen directly outside of Jani's Supplies. In the lower right hand corner is a picture of Doomguy.
In the Dead City Central a poster is seen in the food court advertising a sale on both Doom 5 and, amusingly, RAGE 2.
In Dead City, after picking up the Defribrilator, you will have to fights a couple of mutants and a slime mutant. You will go through an opening through the wall and down a bunch of stairs until you reach a white sofa. Continue on your way and you will reach a room with a door that you have to go through to escape. Next to the door is a graffiti in red and white of the hellish face that looks exactly like the loading screen of the Hell Levels in Doom 3.
Dopefish
This Easter egg is located at the Mutant Bash last arena. The player has to shoot three lights and then a dopefish pops up; shoot that three time as it appears from behind the painted waves to gain bonus money. See video here, and note that this also makes earning the "Bringin' Home the Bacon" Achievement/Trophy much easier.
This fish is dopefish, a popular Easter egg in id Software games. Created by Tom Hall, one of the co-founders, and first introduced in the Commander Keen game, it has made quite a few appearances over the years in games from several developers, including Wolfenstein 3D, Quake, Anachronox, Max Payne, and Hitman 2. It is mostly used as an Easter egg, generally in a secret area.
Fallout references
In Subway Town, the picture in the magazine Dietrich is reading is the mushroom cloud freeze scene seen at the end of Fallout: A Post-Nuclear Role-Playing Game game with the tag line "War, war never changes". The player can also see the explosion and an Enclave eyebot and the surrounding area is faint.
There is a Vault Boy bobblehead Easter egg in RAGE. A rare Vault Boy bobblehead from Fallout 3, another Bethesda title, can be found in Wellspring, on the right side of Mayor Clayton's desk. It seems to be the Charisma bobblehead, which in the game would improve the player's ability to influence other people through dialogue. It might perhaps explain how Mayor Clayton is, or tries to be, so charismatic.
In the Trophy Room, an instrumental version of "Home on the Wastes," a song sung by The Lonesome Drifter in the Aces Theater at The Tops Casino in Fallout: New Vegas, can be heard on the Radio.
Half-Life 2 reference
In Subway Town an Authority guard can be found standing next to a can. Approaching him will cause him to give an order to the protagonist: "Pick up that can!" After the player picks the can up the Authority guard will say, "That's a good boy". This is a reference to Half-Life 2 where a Civil Protection officer tells the players to do the same thing.
Hexen
In the Dead City there is a old news van labeled Hexinews 6. This is a reference to Hexen, a game developed by Raven software and published by id Software using the DOOM engine.
Duke Nukem 3D
In the beginning of the quest "Defibrillator Upgrade" just before the entrance to Dead City there is a room full of slimed corpses. One of the corpses is a nude female in the standing position with her arms attached to a pillar behind her, a reference to women caputured by aliens that Duke must rescue that are often held in a similar position.
In the Mutant Bash TV lobby on one of the monitors behind J.K. Stiles the id logo is seen that plays at the start of the game.
Another id logos — sculptures, one seems to be the Modern Art piece and the other is crafted with several pieces of scrap, — are displayed in the Ghost Hideout and in the middle of the secret Developer Graffiti room respectively.
Yet another id logo can be found on a buggy's side in Wellspring, and can also be bought as a theme for the Dune Buster.
Jan van Eyck reference
In the Abandoned Distillery at the start, there is a pillar with "ЯН БЫЛ ЗДЕСЬ" written on it (video @6:17), meaning "Jan was here", referring to painter Jan van Eyck (Source: Russian Wikipedia article for RAGE).
Lost references
In the Wasted Garage's second floor is a street sign that has "4 8 15 16 23 42" written on it. These are the mysterious numbers that are present in the series.
In the secret Dev graffiti room the phrase "Not Penny's Boat" can be seen on the wall, a clear reference to the series.
Mad Max references
In addition to the obvious post-apocalyptic wasteland setting and Vehicle Combat, there are several items in the game which pay homage to the Mad Max films.
The sawed-off Double Barrel Shotgun included in the Anarchy Edition strongly resembles the weapon Mel Gibson uses in the first two films of the series.
Crossbows are featured heavily in the Mad Max film series.
The Dune Buster and its bandit equivalents are very much in the style of the numerous custom-built buggies and off-road vehicles that appear in the second and third Mad Max movies.
Similarly, much of the clothing worn by various NPCs in the game is clearly inspired by what is seen in the films.
Magic Mushrooms
A patch of blue mushrooms can be found in the Hagar Caves that when acquired, will cause the player's screen to flash multiple colors. This is likely a reference to hallucinogenic mushrooms and drug culture.
They are located in the room with the TNT detonator.
These are an homage to "Twinkies" snack cakes which, according to urban legend, are (incorrectly) said to have an infinite shelf life and thus presumably would still be edible in a post-apocalyptic future. It is also a nod to the original Doom enemy, the Demon, popularly nicknamed "Pinky", due to its coloration; a cartoon monster resembling the Pinky Demon's Doom 3incarnation can be seen on the front of the box. When picked up, the sound file of a Demon snarling can be heard.
Quake references
The Quake room Easter egg is located in the Wasted Garage. Inside there are three buttons the player has to press in order to open a portal. Follow the steps on this video. The Shambler Plush collectible can be found in the secret room.
The Combat Shotgun iron sights form a figure that resembles Quake logo when the player aims down the sight.
Inarguably a reference to the criticism that Quake featured too many brown tones, a box of "Quayola" crayons can be found and collected in the game. This critique was referenced by Ben "Yahtzee" Croshaw in his Zero Punctuation review video of Clive Barker's Jericho, claiming: "id software's original Quake […]. I'm sure with the benefit of hindsight we can all agree that Quake wasn't exactly easy on the eye. Which was your favorite Quake level? The brown castle, the greenish brown temple or the other brown castle?" The name itself is a reference to "Crayola" brand crayons.
Sinclair Motor Oil
In the "Second Chance" bar in Wellspring, there are some signs that read "Rexsor Motor Oil". As the signs are green and have a dinosaur on them, they are likely a reference to Sinclair Motor Oil[citation needed].
Tommy Tu-Tone
In the Wasted Garage, in a bathroom there is a graffiti saying "Tommy + Jenny". Jenny is the girl referenced in the song "867-5309", where Tommy finds Jenny's number on a bathroom wall.
Prey
Possibly, the bathroom graffiti could instead be a reference to the game Prey, which features the main character Tommy and his girlfriend Jenny, Prey opens with the main character in a bathroom thinking about his relationship. The rights to Prey were transferred to Bethesda Softworks and Id Software parent company ZeniMax Media before Rage was released. The game itself also ran on ID Tech 4.
The Darkness "Eating Hearts" reference
In Dr. Kvasir's laboratory, there are two mechanical arms that come out from both sides of the room. When the player places a quest item onto the table, the arms will both attempt to retrieve the item. The animation that occurs is a subtle nod to the original comic-book inspired video game, The Darkness.
Jackie's darkness tentacles fighting over the heart of a fallen enemy.
In this montage video from the original Darkness game, you can see the interaction between the dark eel-like tentacles that are summoned by Jackie Estacado using his darkness powers. In the game, Jackie must devour hearts from fallen enemies to regain his full darkness potential. In these animations, sometimes the two tentacles will fight over the heart, in which the right-hand tentacle will always win. The animation seems to indicate that the right tentacle is dominant over the left, suggesting a direct correlation to which half of Jackie's brain is the more dominant side. (The left brain is responsible for logic, analyzing, and reason; whereas the right brain is attrubuted with intuition, passion, and creativity)
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Mechanical arms fighting over item in Dr. Kvasir's laboratory.
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In this video clip from Dr. Kvasir's lab (RAGE), you can see the animation that occurs when the mechanical arms retrieve the item from the table. The left arm will attempt to grab the item from the right arm's grasp, a slight struggle will ensue, but the right arm will always retrieve the item for the doctor. The left arm will drop itself downward as if to express sorrow at its own defeat. This is an unconfirmed reference, but the similar animations make this an extremely likely nod by the animators to a favorite moment from The Darkness.
