- GTA would not be GTA without the sex refrences, here is one that is in the bowling alley, as a neon sign, if you look close at the picture you can see that it is made out of a one pin and two bowling balls.
- When you go down the stairs of your first apartment you may spot some graffiti referring to past GTA protagonists, Claude, Tommy, Carl, and Toni.
- You may remember Sprunk from GTA VC, GTA SA and Manhunt well its returned to GTA IV with a brand new look. Sprunk is mainly a parody of Sprite but may also be a parody of others, but it also can be argued that the name is also a play on the word spunk. You can find Sprunk scattered all around Liberty City.
- If you ever have the time, visit the Statue Of Happiness (Statue Of Liberty), inside you will able to spot a giant heart actually pumping, the is no reason for being there only just to creap you out.
- In Cluckin' Bell restaurants, near the back of the store, there's a action figure of a man in a martial art position and has a chicken head mask on, printed on the glass is "Cluck Norris", which is a parody of Chuck Norris who is a expert in martial arts and has invented his own martial art and the roundhouse kick.
- Remember in San Andreas on the Gant Bridge "There Are No Easter Eggs Here Go Away", GTAIV has got one saying "No Hidden Content Here", you will find this as you are about to enter the Statue of Happiness.
- If you ever have time to watch T.V in one of your apartments in-game, one of the TV programs called 'Las Ventura's Poker'. you will actually see a casino from San Andreas.
- In many spots around Liberty City, there is rubble on the ground. In some of this rubble you can see a purple dildo sticking out.
- One of Rockstar's rivals has been parody in the world of Liberty City, Saints Row but instead they called it 'Squid Row- Budget Seafood'.
- You may remember Love Fist from GTA Vice City, Well like in San Andreas there is a reference to them on a sign in Star Junction.
- Many street names in Liberty City are named after prisons.
- Leavenworth Ave
- Alcatraz Ave
- Sing Sing Ave
- Guantanamo Ave
- Attica Ave
- San Quentin Ave
- Folsom Way (best known from "Folsom Prison Blues" by Johnny Cash)
- Rykers Ave (from the fictional Rykers Island prison in Marvel Comics)
- Joliet Street
- Once you get your apartment, in Bohan, you can look on the ground next to the coffee table, and infront of the bed. There are a few CD's laying on the floor. Zoom in with a sniper, and of course, one of the CD's is of OG Loc from GTASA.
- You may remeber that hidden content was found in GTA San Andreas which was called 'Hot Coffee', this ended up being a big problem for Rockstar Games, but there laughing about it now with the many refrences they have put in the game. One of them is a sign saying 'Hot Coffee Shop'.
- In Alderney there is a building called "Mr. Wong's". It's a laundromat. Same as in GTA III.
- If you go in any of the TW@ cafes and look at the printer you will see a error 'ERROR UNLEASH NINJA GURU'.
- Crime Scene Investigation has its own parody in GTA IV, called Science of Crime, you can find posters for this all around Liberty City.
- If you look on the walls in the prisons, you will find prision guard names, which are funny.
- Seymour Fani
- Isaac Hunt
- Richard Head
- Phil McRevis
- The mission Weekend at Florian's is a refrence to the comedy movie 'Weekend at Bernie's', (Florian insists that his new name is Bernie.)
- The mission called "I Need Your Clothes, Your Boots, and Your Motorcycle", is a reference to Terminator 2: Judgement Day, in which Arnold Schwarzenegger says this famous line.
- In the amusement Park in Broker there are blue/purple Hippo Statues, just like the ones from Manhunt.
- At the Statue of Happiness at one of the doors, is a t-shirt that reads "Happiness is...... Land".
- When you kill Playboy X, go to his apartment to get clothes that unbelievably resemble Claude's clothes who was the protagonist from GTA III.
- Rockstar Games have a habit of putting their logo in the games, so if you go to a bowling alley and look at the bowling pins you will see that they have the Rockstar logo on them.
- If you look at any newspaper in the game you will see a familiar face on the front, it none other than Donald Love, who if you remebered dissapeared in GTA III.
- if you look at the golf courses carefully from a height you may notice that they are penis shaped.
- The securicars in GTA III had the words Gruppe Secks on, the ones in GTA IV have a similar one saying Gruppe 6.
- This is a parody of 24, a popular TV show in America on the TV Channel FOX starring Kiefer Sutherland. Also the clock that is used to say the numbers "72" is reference to the ABC show Lost.
- When you enter any of the bars in Liberty City you will see postcards of Vice City.
- There's a brand of beer in the game called ' Dusche Gold'. Dusche is German for Shower, it means Golden Shower.
- Burger Shot is another restaurant returning in GTA IV, this is a parody of Burger King.
- In Trailer 2, you can see two artworks from previous GTA's on the side of a building or wall. El Burro from GTA III and the motorbike from Vice City.