This page lists all known Easter eggs that can be found in Hitman: Blood Money.
Each time you load the menu, you can see some of 47's targets sitting in the church that appears in the last mission, Requiem. Near 47's coffin, sits Alexander Leland Cayne, who was the main antagonist.
When the player progresses through missions, the targets he has killed will disappear from the church. After the game has been cleared, the camera will pan on Agent 47's deathbed, and will not return to normal unless the player restarts from the mission A Vintage Year or Death of a Showman and quits.
This Easter egg can be found in Agent 47's hideout. There are numerous rats in the hideout, and after you kill them all a window will appear, displaying the message "You sent all the rats to a happy place in (time that you needed to kill them)".
When you are in the basement, in one of the rooms, you will see rats (and also a worker complaining about them). When you kill all of them (it's recommended that you use a silenced pistol since someone might hear the gunshots), a Rat Club Keycard will appear on the table. If you pick it up and go to the second floor, you'll see another worker who periodically tries to open a door but with no success.
Use the Rat Club keycard on the door and you will enter a room with rats doing multiple tasks, such as playing cards and boxing. This is a reference to the Dogs Playing Poker series of paintings by C.M. Coolidge.
Phantom of the Opera
In the basement of the Curtains Down mission, the mask from "The Phantom of the Opera" can be found sitting on a cabinet shelf. This could be a reference to the story, where the Phantom hides in the cellars beneath a Paris opera house (like where the mask is found).
United States of America
Tiny Mouse vs. Mazy
Tiny Mouse vs. Mazy is a comic book. It can be found on Vinnie Sinistra's computer desk on the second floor of his house. Vinnie will also sometimes come up and sit in front of the computer.
Dancing FBI Agents
There are two bottles of lighter fluid scattered throughout the level (one in the basement and one in the tool shed). If you have the pool boy outfit and talk to Vinnie's wife, she'll invite you upstairs. Afterwards, she will fall asleep. Take her necklace, then rig the barbecue next to the pool with both bottles of lighter fluid.
When Vinnie's wife comes down and messes with the barbecue she will light on fire. If done correctly, the guards will come next to the pool and start clapping, doing a synchronized "wave" movement among other things as well.
Dancing Assassin (#1)
On the level The Murder of Crows, in one of the clubs, (rock, blues or salsa) if the player doesn't move for a while, Agent 47 will start dancing.
On the second floor of the engine room, throw a guard down the right side of the railing and a member of the Gator gang down the left side. Now people will act like zombies. They will walk slowly, hit you when you're near them, and walk zombie-like (the same animation that happens when a character drags a body). They can be killed but after some time they will rise again, unless shot in the head.
If the player goes to the group of guests which are having a fighting competition, then goes northwest (on the compass) and shoots a very small silver disc-shaped object near the water, the group of guests which have previously been fighting each other will become naked and run towards you, clapping in the process. After some time, they will resume the fighting, though they will still be naked.
Dancing Assassin (#2)
When Agent 47 is moved to one end of the dance floor, and stays still a certain amount of time, the dancing will continue and Agent 47 will join along.
There will be a large building in front of Agent 47 when the level starts. If the player enters the building straight ahead, he will see a receptionist. The computer the receptionist is working on displays Hitman: Codename 47's website.
You need a marine suit and the lady's briefcase (the one that goes for a smoke near the bus at the beginning of the mission)
In the wing in which Morris initially can be found, is a hall with a fireplace that isn't lit. Throw the briefcase at the fireplace three times. If done correctly, the marines will all form a line and start dancing the can-can.
The Presidential Candidates
In the newspapers which are shown after completing a mission, there are often statistics related to the people running for presidency, in one of the corners of the newspaper.
One of the candidates is named "N. F. Chance". This most likely stands for "No Fucking Chance", as he is booted out of the race very early on. Another one is "Governor H. Behind" (which could possibly be a reference to the 41st president of the United States, George H. (W.) Bush).
Candidates are also subtle references, most notably "F.C. Klark" (FCK or FC Copenhagen, the preferred international football team of Io-Interactive), whose name also appears on all the TV's in the hotel rooms in the mission A House of Cards. A third candidate is named "Lance O. RegenT", or shortened, LORT, which translated from Danish literally is "shit".
The newspaper will also show minor references, such as an article that states that two prisoners escaped from prison (while detailing the events, a clear reference to Io-Interactive's title Kane & Lynch: Dead Men), what happens to Margeaux LeBlanc after the events of Till Death Do Us Part, and that the Cheung Chau Fish Restaurant is reopening, with special meals such as the "Blue Lotus Soup".
Another series of things in the newspapers are the articles about your contracts themselves. You can get special ratings (such as Mad Butcher), and if you kill enough people in the mission (all shots must hit the intended target), the article will say that the killer's accuracy resembles the accuracy of the "Legendary 47."
There are also various objects and scenery with references, such as books with the Hitman insignia on it, and various car number plates (plates that say BLOODMONEY, plates that say IO INTERACTIVE, etc.). In A New Life. on one of the plates says "BADBLOD". Many believed that this was a mistranslated for "Badblood". However translated backwards, "BLODBAD", which translates to Danish (and Swedish) for Bloodbath.
It might look like there was an influence from a famous french movie "Le Samourai" (1967). The protagonist, Jef Costello (Alain Delon) is a hitman who lives in a single-room Parisian apartment whose spartan furnishings include a little bird in a cage. There was a scene where the police bugged his room, which agitates the bird in its cage. Upon returning, Costello notices some loose feathers scattered around the cage and the bird acting strangely. Suspecting an intrusion, he searches his room, finds the bug and deactivates it. This looks a bit similar to the scene before the Requiem mission, where the canary starts agitating and 47 suspects somebody's presence.