Go to the multiplayer map "Airfield". Go to the first side, which is the one where you spawn behind the big building then go out to the field. Instead, go inside the building and examine it. Look around at the pillars and windows, then go upstairs to the left. Look around some more and on the balcony. Notice it is the same building in the Nacht Der Untoten (zombie) mission, except all the entrances are walled up or blocked by an invisible wall.
Asylum: Ghostly piano record
Above the bathroom in an invisible room, a piano can clearly be heard being played on a record player. The piano can only be heard if you music setting in the options menu is on.
Asylum: Strange sounds
You can also hear a disembodied voice near the bathroom. It comes from just outside of the bathroom, and is best heard in Spectator mode.
Just outside of the bathroom on Asylum, exactly where the disembodied voice is heard, you can also hear a crying girl. She will switch back and forth from crying to laughing, and just like the voice, is quite disturbing.
All around the stairs that are a bit away from where the piano can be heard, you can here knocking on the wood that is covering up all the windows. If you fly around constantly as a spectator, you will hear this wooden knocking sound everywhere. It distinctly sounds like someone deliberately knocking on wood. It can also be heard on the boarded up windows on the other side of the map.
Cliffside: Mysterious shrub
Go into Spectator mode on Cliffside and look down the cliff at the beach. To the left, you should see a small crater on the beach where a mortar shell has hit. Fly down through the crater and keep going down. Eventually, you will go into some invisible water. Come up out of the water a bit and look around. You should see a large bush nearby in the mist. It is just floating there very far under the map.
Cliffside: Strange voice
On the Japanese spawn side of the map are two concrete bunkers. Go into the one at the top of the hill (with Japanese Flags on it) in Spectator mode. Go through one of the little windows into the back area of the bunker. Turn around and turn up the volume. You should hear a strange garbled and quite disturbing voice coming from the wall. It is a disembodied voice.
Dome: Big crowd
Go into the large pit as a spectator, and you will hear the Red Army shouting their battlecry of "URA! URA! URA!". Oddly enough, you cannot hear them at all from within the actual map boundaries (unless you are unfortunate enough to fall in).
Downfall: Animal shadows
Go to the map in Spectator mode. Look for a drivable tank to the left and in front of two trucks. From there, it should be exactly next to the destroyed building you are looking for. Make sure the truck behind the tank is in front of a destroyed Flak cannon, and the building is to the left according to the direction of the tank. After you find the building notice that the walls are divided into squares or segments. And keep note the correct building is not alone; it is connected to a series of buildings. Line up the tank exactly with the square segment it is next to on the building. Look carefully at the shadows and notice how they fade out the walls. If you look carefully enough looking at the whole wall square, you should see a chicken with its wings in the air with big bulging eyes. Two segments over you should see a fat pig standing up and smiling.
Extra custom weapon slots
Reach the indicated prestige rank to unlock the corresponding extra custom weapon slot.
6: First prestige.
7: Second prestige.
8: Fourth prestige
9: Seventh prestige.
10: Tenth prestige.
Getting more ammunition
Use the following trick if run out or are running low on ammunition on any mission in Solo mode. Find a non-essential teammate (someone not involved in the story line). Walk up to him and aim the reticule next to his head or torso. Knife the air, and as you do so move slightly towards them so that the reticule is over them. If done correctly, your teammate should die and should drop his weapon. The difficulty setting will not matter. Non-essential teammates will get replaced when you walk into a battle. If the teammate does not die but keeps getting back up, they are essential to the story (for example, Sgt. Roebuck and Sgt. Rezenov).
Hangar: Torture chamber
In the bottom of the two story tin building on the Marine's spawn side is a jail cell with a dead tortured Russian soldier in it. Coming from the door in the cell, you can periodically hear a Japanese person torturing another soldier.
Little Resistance: Ray gun
After the boat crashes, call in an air strike on the specified location. Run up to the beach and move to the right. You will find a small puddle at the right side of the beach. Stand in it briefly, then move towards the middle of the beach to find a smaller puddle. Stand in that puddle briefly. Move towards the far left side of the beach. Stand briefly in the puddle in the barb wire. After several seconds the screen will shake and you will hear strange voices. Four lion statues will rise out of the ground with alien ray guns in their mouths.
Multi-player kill streak bonuses
Kill the indicated number of enemies in a row to get the corresponding bonus.
3 enemies: Recon plane displays enemies on your team's radar.
5 enemies: Artillery strike that can placed anywhere on the map.
7 enemies: Send out an angry pack of dogs against the enemy.
Nacht Der Untoten: Hidden radio music
Start any sort of Nazi Zombie game and unlock the door to the Mystery Box room. Go to the Mystery Box. Go over to the right and look at a table to find a radio. Shoot a bullet at the radio then wait a few seconds. You will hear random sorts of music such as rock, disco, opera, and some in game music such as the Russian victory song, the last level music, or the Japanese combat music. The music will stop in between rounds but will then start again. Every player in game can even hear it.
Online Multiplayer Unlockables
Reach the following ranks on Multiplayer to unlock the desired Multiplayer unlockable.
Multiplayer unlockable
How to unlock
.357 Magnum
Reach Level 49
Arisaka
Reach Level 4
Bandolier
Reach Level 40
BAR
Reach Level 4
Bomb Squad
Reach Level 16
Bouncing Betty x2
Reach level 24
Browning M1919
Reach Level 61
Camoflauge
Reach level 12
Colt M1911
Reach Level 3
Custom Class Slot 10
Reach Prestige Level 10
Custom Class Slot 6
Reach Prestige level 1
Custom Class Slot 7
Reach Prestige Level 2
Custom Class Slot 8
Reach Prestige Level 4
Custom Class Slot 9
Reach Presige Level 7
Dead Slience
Reach level 52
Deep Impact
Reach Rank 1
Double Tap
Reach Rank 36
Double-Barreled Shotgun
Reach Level 29
DP-28
Reach Level 13
Extreme Conditioning
Reach Rank 1
FG-42
Reach Level 45
Fireproof
Reach Level 48
Fireworks
Reach evel 1
Flak Jacket
Reach Level 1
Gas Mask
Reach Level 2
Gewher 47
Reach Level 6
Juggernaut
Reach Level 4
Kar98k
Reach Level 41
M1 Garand
Reach Level 17
M1A1 Carbine
Reach Level 65
M2 Flamethrower
Reach Level 65
M9A1 Bazooka x2
Reach Level 2
Martydom
Reach Level 20
MG-42
Reach Level 33
Mosin-Nagant
Reach Level 21
MP-40
Reach Level 10
Nambu
Reach Level 1
Overkill
Reach Level 56
PPSh 41
Reach Level 53
Prestige Mode
Reach Level 65
Primary Grenades x2
Reach Level 44
PTRS 41
Reach Level 57
Satchel Charge x2
Reach Level 1
Second Chance
Reach Level 9
Sleight of Hand
Reach Level 28
Special Grenades x3
Reach Level 1
Springfield
Reach Level 3
Steady Aim
Reach Level 1
STG-44
Reach Level 37
Stopping Power
Reach Level 1
SVT-40
Reach Level 1
Thompson
Reach Level 1
Tokarev TT38
Reach Level 21
Toss Back
Reach Level 6
Trench Gun
Reach Level 2
Type 100
Reach Level 25
Type 99
Reach Level 1
Walther P38
Reach Level 2
Perks
Complete the indicated task to unlock the corresponding perk.
Perk Slot 1
Special Grenade x3: Reach level 4 (three special grenades, no smoke).
Satchel Charge x2: Reach level 4 (two remote detonation explosives).
M9A1 Bazooka x2: Reach level 4 (bazooka with two rockets).
Bomb Squad: Reach level 16 (seek out enemy explosives).
Bouncing Betty x2: Reach level 24 (two pressure activated mines).
Bandolier: Reach level 40 (extra ammunition magazines).
Primary Grenade x2: Reach level 44 (two primary grenades).
M2 Flamethrower: Reach level 65 (projects a controlled stream of fire).
Perk Slot 2
Stopping Power: Reach level 4 (increased bullet damage).
Fireworks: Reach level 4 (higher explosive weapon damage).
Flak Jacket: Reach level 4 (reduce explosive damage).
Gas Mask: Reach level 4 (protect against Tabun Gas).
Juggernaut: Reach level 4 (increased health).
Camouflage: Reach level 12 (undetectable to enemy recon planes).
Sleight Of Hand: Reach level 28 (faster reload).
Shades: Reach level 32 (reduce intensity of signal flares).
Double Tap: Reach level 36 (increased rate of fire).
Overkill: Reach level 56 (carry two primary guns, no pistol).
Perk Slot 3
Deep Impact: Reach level 4 (deeper bullet penetration).
Extreme Conditioning: Reach level 4 (sprint for longer distances).
Steady Aim: Reach level 4 (increased hip fire accuracy).
Toss back: Reach level 6 (reset fuse of picked up grenades).
Second Chance: Reach level 9 (revive downed allies).
Martyrdom: Reach level 20 (drop a live grenade when killed).
Fireproof: Reach level 48 (reduce fire based weapon damage).
Dead Silence: Reach level 52 (less sound when you move).
Iron Lungs: Reach level 60 (longer breath hold while sniping).
Reconnaissance: Reach level 64 (show enemy dogs, artillery, and tanks).
Vehicle Perks
Water Cooler: Reach level 4 (decreased turret overheat).
Greased Bearings: Reach level 4 (increased turret rotation speed).
Ordnance Training: Reach level 12 (decrease reload time of turrets).
Lead Foot: Reach level 28 (increases tank top speed).
Coaxial Machine Gun: Reach level 40 (driver controlled machine gun).
Ray Gun
To get the ray gun you must play the mission "Little Resistance". When you get to the main laid on the mission, you will find 4 holes. The holes will be in a row and step in each of them from right to left. When you get to the last hole, 4 statues will come out of the ground. Each of the statues holds a ray gun for you to take.
Saving Private Ryan reference
There will be a section where you will be asked to "Save Private Ryan". This is a reference to the critically acclaimed film Saving Private Ryan.
Veteran mode
Reach Level 32 to unlock Veteran mode, which is a Co-op mode with much tougher enemies.
Weapons
Complete the indicated task to unlock the corresponding weapon bonuses.
