Trivia: Metal Gear Solid 4: Guns of the Patriots
- Actor Allusion: Drebin has too much in common with Smuggler for it to be a coincidence: same voice actor, same appearance and wardrobe, same job description.
- Ascended Meme: A few of them in the PS3 Trophies. Including "Hurt Me More!" for electrocuting someone with your stun knife.
- Casting Gag: The recasting of Big Boss counts as this in the original Japanese version. As Big Boss is Solid Snake's father, he's played by Akio Ohtsuka's real life father.
- Creator Cameo: Kojima appears in the intro Bomb Shelter Buffet TV segment, as well as in a hidden flashback during the confrontation with Psycho Mantis' ghost.
- Defictionalization: Sony released a bluetooth headset styled after Snake's Solid Eye around the game's release, which was even compatible with the game itself and could be used to listen to Codec calls.
- Dyeing for Your Art: David Hayter's voice for Old Snake featured age-based vocal decay, taking the Guttural Growler trope Up to Eleven. It apparently gave him trouble doing Naked Snake's voice again in Peace Walker.
- Fan Nickname: "Movie Gear Solid", for its high Story-to-Gameplay Ratio.
- Hey, It's That Guy!: A somewhat recursive cameo, the intro TV segments include David Hayter being interviewed by Lee Meriwether; both not only play versions of themselves in the clip, but they both star in MGS4 as Old Snake and Big Mama/EVA respectively.
- Hey, It's That Voice!: Since when did Cyborg become a gun launderer?
- Ho Yay: Vamp and Raiden in Act 2. Who do they think they're kidding?
- Meme Acknowledgment: According to David Hayter, the voice director on the games brought in Metal Gear Awesome for the cast to watch together during the recording of this game. Following this, Hayter and Egoraptor met at Anime Expo. This was the result.
Snake: Omigod, hotness. I wanna bang you.
Snake: I wanna bang you too. Right back at ya.
- Talking to Himself: Averted. Being the first game since the MSX2 era to feature both, Solid Snake and the elder Big Boss, the latter's role is played by Richard Doyle (the voice of The Fury) in the English version, and in the Japanese version by Chikao Otsuka (Akio Otsuka's real life father).
- What Could Have Been: The game had a bigger emphasis on the factional warfare between the PMC and whatever rebellion is in the area, and the war aspect was more played up, with the war afflicting the environment - and thus, places to hide, such as tanks blowing out buildings or the vehicle you're hiding in being driven off to fight. Enemies didn't even sound an alert when spotting you - they shouted to inflict Psych damage.
- In an "MGO Eyes" video, it was revealed that Metal Gear Online had three additional maps that did not make it into the game: the first being "Desert Duel," the second being a recreation of the Town stage from Metal Gear Solid: Portable Ops that was never officially named, and the third is "Lethal Leviathan," which was actually the ship bow of Outer Haven. The first and third were eventually added to the game's arcade version, Metal Gear Arcade.
- Not from the game itself, but there was originally going to be more novels besides the novelization for this game written by Project Itoh, specifically Snake Eater and Peace Walker. Obviously, these plans were dropped as a result of Project Itoh's death from cancer. Novelizations for these games were eventually made by other authors.
- Originally, Johnny's grandfather (also named Johnny) was going to appear at the wedding, confirming that he did survive Metal Gear Solid 3 and Portable Ops. Unfortunately, this never made it past the concept art stage.
- Writer Revolt: Originally, Kojima wanted to end the game with Snake and Otacon turning in to authorities only to be executed for being terrorists. His staff flat out refused to work on the game if it was to end that way.