The following are a list of secrets found in the Tom Clancy's Splinter Cell series.
Meeting Grímsdóttir Edit
In the Training level, the player can make their way up to the observation platform overseeing the basic assault course. Once the player begins the level, they can climb up to the upper levels located to the left of them as soon as the level starts. Once they climb up, looking to the left will reveal a door with keypad lock next to it. Entering in the code 5656 will unlock the door, and allow the player to walk inside of the observation platform room. Inside, Anna Grímsdóttir will be in the far room looking at the window. The player can talk to her, providing an introduction and some info regarding Second Echelon.
Hidden Lock Pick Kit Edit
The player can find a hidden Lock Pick Kit located inside of a maintenance closet inside of the basic assault course room. Once the player starts, they can look to the right to find an upper platform area. They can perform a wall jump and climb onto it. The player can then look to the right and find the maintenance closet, inside of the closet will be the hidden Lock Pick Kit (which wouldn't be available until the Covert Operations training in the next area). This Lock Pick Kit can be used on the locked door at the end of the basic assault course (located on the right). Inside of the small room is a computer containing a data stick, an email between Irving Lambert and Grímsdóttir.
Secret Medical Kit and Disposable Pick Edit
In the Defense Ministry level, the player's second objective will be to interrogate Vyacheslav Grinko's driver, Hamlet, in the parking lot at the base of the Georgian Ministry of Defense Headquarters. Once the player enters the stairwell, instead of going down the stairs, the player can go up one level from where they entered. The player can find a Medical Kit at the top of the stairs, but looking behind them will reveal a metal beam above the player. The player can wall jump onto the metal beam, and then jump onto another metal beam. Looking behind them, the player can find another metal beam and jump onto it. From there, they can see a small platform (with a pallet located next to it). The platform will be holding a Medical Kit and a Disposable Pick the player can pick up.
X-File Reference Edit
In the CIA HQ level, the player is tasked with following CIA employee Mitchell Dougherty to the smoking courtyard. At some point, the player will follow Dougherty through some double doors (with a keypad lock). Once on the other side of the doors, the player will be inside of a hallway - with Dougherty traveling to the right towards the smoking courtyard. Instead of following Dougherty, the player can go the other way and will encounter a door labelled "UFO Sightings". The player can pick the lock and get inside, revealing a small room containing a desk with a laptop. If the player types the laptop, they will receive a data stick containing an email sent to "F.M" at the FBI, following a series of repeated numbers. The numbers are the code for the keypad lock for the other door in the room. Entering in the code will unlock the door to another room containing gadgets and numerous rows of filing cabinets behind a caged wall.
Rayman in Vending Machines Edit
In the CIA HQ level, after the player aquires the SC-20K M.A.W.S., the player will reach a break room with four vending machines located inside (a CIA employee is also in the room talking on the phone). The player can use their SC-20K scope to zoom in on either of the two middle vending machines, revealing a blue bag labelled "Rayman" with a picture of Rayman, one of Ubisoft's most iconic characters.
In the first level, US Embassy, the player can trigger a humorous conversation between Sam Fisher and Irving Lambert at the start of the mission. If the player doesn't climb up onto the dock, but instead runs around the small space, in certain intervals, this conversation is triggered:
Lambert: "What are you doing Fisher?"
Sam: "Heading out to sea."
[If the player runs around a little more, another conversation triggers.]
Lambert: "What the hell are you doing?"
Sam: "Trying to convince you it's time to let me retire."
Lambert: "That's not funny."
[If the player runs around a little more, the final conversation triggers.]
Lambert: "This is not amusing. You're carelessly putting lives at risk. Get back to shore, Fisher, you've got a mission."
Three Alarms Failure reference Edit
Once the Cargo Ship level begins, both Sam and Lambert will make a passing reference to the previous alarm system in the first Splinter Cell as well as Pandora Tomorrow. Lambert explains to Fisher that the guards likely have an alarm system set up on the Maria Narcissa, to which Fisher sarcastically asks, "Let me guess, three alarms and the mission's over?" Lambert replies, stating, "Of course not. This is no video game."
Half-Life reference Edit
In the Battery level, when Grimsdottir tells Sam that he needs to open the casing before he could tap into the BIOS, Fisher replies "I didn't bring my crowbar." Then Grimsdottir says "Whatever... crowbars are for geeky video-game characters." This is an obvious reference to Gordon Freeman from Half-Life series, whose signature weapon is a crowbar.
Prince of Persia reference Edit
In the level Displace, Prince of Persia is briefly mentioned by two guards. One guard is taking care of an apartment for a guy he knews, mentioning that, "He has the new Prince of Persia" and stating that it'll be, "Game of the Year." This is likely referring to Prince of Persia: The Two Thrones, which released the same year as Splinter Cell: Chaos Theory released.
Brazil (1985 film) Edit
In Displace level, Sam interrogates a guard, saying that he's, "Harry Tuttle." The guard asks who that is, to which Sam replies, "I'm an ill-tempored, heavily-armed engineer asking about your ventilation system." This is a clear reference to the 1985 film, 'Brazil'.
Metal Gear Solid reference Edit
In the Kokubo Sosho level, if Sam grabs and interrogates a guard patrolling the escalator area, he will patronize Fisher when asked about his specialized shock rounds, saying "it's not like you can shake me and make my ammo fall on the floor." This is a reference to the mechanic in the Metal Gear Solid serieswhere incapacitated enemies can be shaken to get ammo and other supplies from them.
UFO Sighting Edit
In the multiplayer map Museum, the player can spot a UFO. Playing as a spy, the player must enter inside of the museum and head towards the room with the large staircase. Once inside, the player must head up the the staircase to the top and face towards the billboards. The player then much climb over the railings and grab onto the billboard, then climb over the billboard and to land on the floor. Next, the player must run back to where they started the map and to look towards the buildings opposite to the museum and may see the UFO fly by. The player may be able to equip their binoculars and zoom in on the UFO to hear it hum.
Save the Seals Edit
There is a secret side-mission in the co-op campaign that tasks both players with rescuing baby seals. See here: Splinter Cell Double Agent Seals Liberation.
Archer's single player appearance Edit
When infiltrating Kobin's Mansion, the player can find two body bags in the main lobby with the chandelier (the foyer area). If the player looks closely, the player can spot two body bags with one of them showing Archer's head sticking out of one of them. Additionally, the nearby guards will discuss Kobin's actions towards the end of the co-op campaign, referencing Archer's demise.
Rayman Raving RabbidsEdit
Throughout the main campaign, there are instances where the player can find toy figures representing the Raving Rabbids seen from the Rayman franchise. They can be seen most prominently at the Washington Monument fair level as well as the final attack on the White House, where they can be found in rooms Fisher finds on while storming the main path to the Oval Office.
St. Petersburg Banya Edit
If the player is playing Deniable Ops, they can head to the final area zone of the St. Petersbug Banya. There will be a hallway with a room located at the end. The player can then enter into the far room and on the table of the room will be a hat with the logo of the New Orleans Saints football team on it.
Insurgent Stronghold Edit
Aliens reference Edit
In the opening cutscene for Insurgent Stronghold, Andriy Kobin says "If you want 'em dead so bad, why don't you justnuke the place from orbit?". That last part is a reference to the 1986 movie "Aliens", in which the character Ripley states, "I say we take off andnuke the entire site from orbit. It's the only way to be sure."
Special Missions Edit
Splinter Cell 1 reference Edit
The way that Sam evades the firefight with the Iranian forces at gunpoint through an orchestrated blackout is a direct reference to the final level of the original Splinter Cell, where Sam is provided a similar blackout by Lambert to gain the upper hand in an overwhelming firefight.
Chaos Theory sneaking suitEdit
The sneaking suit that Sam used in Chaos Theory is available through downloadable content where it is labled as the "Upper Echelon Suit". It great increases the stealth statistic while also providing some protection against damage.
Gone Dark mission referencesEdit
Several missions that take place on the SMI make references to the the past criminal/terrorist organizations that Sam faced in previous games. This includes the JBA, Tom Reed's Third Echelon Conspiracy, and Megiddo.
Mass Effect ReferenceEdit
In the debriefing of the Lumber Mill mission, Grim will ask Charlie to do calibrations. This could be a reference to Garrus Vakarian from the Mass Effect Universe who frequently said that he was in the middle of 'calibrations'. Like Charlie, Garrus is a weapon modification expert. Also, the Paladin and the SMI reminds of the Normandy and the Galaxy map.