Due to Hideo Kojima's love for breaking the fourth wall, and the fact that the game is set in the past by a few decades, Metal Gear Solid 3: Snake Eater is rife with this.
- One of the most well known, infamous call forwards happens if you kill either Ocelot or EVA in the game. As many know, when Naked Snake dies, the game over screen reads "Snake is Dead" and the letter stems disappear and reappear in other places to eventually form the phrase "Time Paradox" (because of Naked Snake's obvious importance in creating the other protagonists in the series). However, if you kill Ocelot or EVA, you get the "Ocelot/EVA is Dead" message, but instead of the normal contacts yelling out for Snake, you have the Colonel Roy Campbell (of MGS1 and MGS4) saying something like "Snake, what have you done? You changed the future!! You've created a time paradox!" or "You created a time paradox. Snake, you can't go changing the future like that!"
- It's tongue in cheek for this sort of Easter egg to be included for Ocelot, since everyone knows the role he takes in the entire series. But this to come up for EVA (instead of just one of your contacts berating you about letting her die as other MGS games might for those you can't let die) is a major clue that she would play a pivotal role in the course of the series, and Kojima probably meant to clue in players here that she might have a major role to play beyond just the third game.
- It's probably cluing in about Eva's mission of getting the Philosopher's Legacy, but since she got a fake version of the info she needed, it's not that. What is it? Well, keep in mind that she's in Metal Gear Solid 4 as "Big Mama", and she ends up being the surrogate mother for the other three Snakes (Solid, Liquid, and Solidus). So, perhaps this was a VERY clever way of telling us that not only was Eva going to be a very important character in the series, but that Kojima was considering a fourth MGS game to begin with.
- In the HD remaster, if you kill Ocelot when he's unconscious after his first appearance, you get a trophy titled "Problem Solved, Series Over".
- It's tongue in cheek for this sort of Easter egg to be included for Ocelot, since everyone knows the role he takes in the entire series. But this to come up for EVA (instead of just one of your contacts berating you about letting her die as other MGS games might for those you can't let die) is a major clue that she would play a pivotal role in the course of the series, and Kojima probably meant to clue in players here that she might have a major role to play beyond just the third game.
- Naked Snake and Para-Medic discuss Invasion of the Body Snatchers (1956). Snake dismisses human cloning as 'sci-fi nonsense'.
- Snake is also astounded at the idea of "a movie where you control the characters".
- Naked Snake at one point tells EVA that "I've never been interested in anyone else's life", inadvertently quoting his son from the first Metal Gear Solid.
- One of his first lines to Para-Medic after landing in the Virtuous Mission is likewise another quote of Solid Snake's from the first game, responding to her asking what his real name is by telling her "a name means nothing on the battlefield. After a week, nobody has a name."
- Another line from the first game is If the player goes to the effort of destroying the Hind helicopter at the relay station before going up the mountain, he'll quip Solid Snake's line from the Hind-D fight in the first game, "That takes care of the cremation."
- The constant use of the phrase 'in the 21st century' means an awkward attempt at a Real Life version of this will occur.
- During a codec call with Para-Medic discussing James Bond films, Major Zero interjects and declares "I wouldn't be surprised if they made 20 more of those movies."
- A subtle one would be the gun sight on the player's replacement M1911A1, which is the same as Snake's SOCOM in earlier games.
- It ends the same way as the original Metal Gear Solid: Ocelot places a secret phone call where he reveals that he's actually a triple agent for the U.S. government.
- Ocelot's boss battle has a counter displaying how many shots he has left in his revolvers akin to his original fight in the first Metal Gear Solid. He's even the first boss fought in both games.
- The things The Boss says to Naked Snake before and after they fight (particularly about how the survivor will carry on fighting) are highly reminiscent of the things Big Boss would go on to say to Solid Snake. The relationship between the two pairs is actually pretty similar as well, with the difference being that Big Boss actually is Snake's father, and Snake doesn't feel much remorse for killing him, because he actually was a traitor.
- When you pick up the Sneaking Suit, call Sigint and he'll mention that the suit should be the official uniform for the FOX unit... which it obviously later does become.
- "The password is... 'Who are the Patriots?' and 'La-Li-Lu-Le-Lo.'" As the next game reveals, this turns out to be a clue to the identity of the Patriots and borders on Something Only They Would Say.
- In the HD edition, the achievement for a Pacifist Run is called Peace Walker.
- Hmm... Raikov does look like someone very familiar....
- Not only that, but at the beginning of the game, the game asks you if you liked Metal Gear Solid 1 or 2. If you choose 2, then Snake begins the game wearing a mask that makes him look exactly like Raikov... and that one other dude. And his nickname is Jack, of all things, which is the same name of that dude from MGS2 that the mask also resembles.
- When Snake meets Granin, the inventor of the Metal Gear series, it's shown that he's already drawn up blueprints for Metal Gear REX and plans to send it to his American friend Huey Emmerich as well as a model of RAY.
- A Codec call with Sigint right afterwards reveals that someone wrote a paper on bipedal tanks. Sigint can't remember if the guy's name was Emerson or Heinrich, but notes that the idea is somewhat pointless and the paper was dismissed.
- In her first call, The Boss makes mentions of how Snake will have to struggle with what he's ordered to do, and his own emotions, which is indeed what happens in the game and sets Snake on the way to becoming Big Boss and founding Outer Heaven. She also mentions how "government and those in charge change", foreshadowing the rise of the Patriots, and how enemies and allies are relative terms and one can become the other, foreshadowing not only her own defection, but also Big Boss and Major Zero becoming enemies in the future.
