Adam Westing: A minor example is the host of Non-Stop Pop referring to herself as "Cara with the eyebrows," voiced by Cara Delevigne.
Approval of God/Official Fan-Submitted Content: If Rockstar Games approves of a player-created race or deathmatch map made with their Level Editor, it will become "Rockstar Verified" and easily accessible in-game to everyone playing Online. Additionally, they regularly feature videos and crews made by members of the Social Club community on their website.
Banned In Australia: Averted on current gen, surprisingly enough, with the uncut game getting an R18+ rating. A mild example for next gen when the Australian branches of Target and Kmartnote Both owned by Wesfarmers (whose company policy bans R-Rated content anyway) and unrelated to the American chains both chose not to stock the game after an uproar caused by this petition, which claims that the game rewards players for committing acts of sexual violence against women (killing escorts after using their services, etc.)
The Next-Gen version has a variation. All the new songs added to the game were handpicked by their respective DJs, instead of Rockstar themselves. Meaning that Cara picked the new songs for Non-Stop Pop, Loggins picked the new songs for Los Santos Rock Radio, DJ Pooh picked the new songs for West Coast Classics etc. Many fans agree that the new songs are a massive improvement over the originals.
Real gangbangers were also called upon to graffiti up memorials of fellow members who have died.
Dawson Casting: Shawn Fonteno was 42 years old when he played the role of Franklin, who is 25 during the events of the game.
Dueling Games: With Saints Row IV, which came out a month before. Despite Saints selling well and getting positive reviews, GTA completely trounced it, both in reception and sales.
Saints Row still got a good one over by releasing the "GAT V" DLC on the same day as the console release, making a stand for PC gamers by offering it for free on that day. (Also eventually by having the expansion and the bundled next gen port out before GTA reached the PC).
One year later, the Next-Gen port of GTA V competed with Far Cry 4 as both are open-world games being released on the same day.
Shortly after the game's announcement, Rockstar stated that like in Grand Theft Auto IV, you would not be able to purchase property. That element has since been confirmed. Although, this was most likely done so Rockstar wouldn't spoil any gameplay until they were ready to announce it.
After specifically stating that Packie McReary wouldn't be in the game, who should appear? Packie.
Before Grand Theft Auto V was originally released on the PS3 and Xbox 360, Rockstar specifically said that it would not be released on next-gen consoles. Come E3 2014, and GTA V was announced for both consoles, with so many improvements, additions, and enhancements that many agree that the next-gen versions are the true version of the game. This wasn't a surprise to most people however, because most assumed that this trope was in effect.
Fans were predicting that the game would have multiple playable characters not long after the first trailer came out, going by said trailer's focus on different people at different points. It was nearly a year later when Rockstar confirmed this.
On GTAForums, an entire thread (warning: the thread is hundreds of pages long) was devoted to mapping out the game's play area, going by what information could be gathered from screenshots and trailers. What they came up with turned out to be quite similar to the snippets of the map that were revealed with the announcement of the game's special editions; compare the last map made before the reveal to this semi-official map◊ (put together from the aforementioned snippets). Likewise, their guesses as to the layout of the countryside were confirmed◊ when the full official map (taken from a strategy guide) was leaked.
Fans were expecting the game's multiplayer component, Grand Theft Auto Online, to be somewhat similar in style to an MMORPG, with more robust character customization than the last game's multiplayer, a free roaming "lobby" similar to the multiplayer of Red Dead Redemption, the ability to customize and store cars, and multiplayer heists. This and more has all since been confirmed.
The PC version. For around 9 months, GTA V was the Holy Grail and the forbidden fruit of PC gaming... until E3 2014.
Promoted Fanboy: Hannibal Buress has said in the past that he's a big GTA fan, and even did a bit about IV in his stand-up; ironically, he got his cameo on FlyLo FM from Flying Lotus himself being a big fan of Hannibal's comedy.
"Radio Ga Ga" by Queen was already highly popular, but after the Michael trailer it surged in popularity, with most of the comments for it on YouTube being related to this game.
"Hood Gone Love It" by Jay Rock and Kendrick Lamar. Its views on YouTube tripled in less than a week after being featured in the Franklin trailer.
Any song featured on the in-game radio stations count. Find any one of the songs from any of the stations on YouTube, guaranteed you will find someone, sometimes the top comment, saying they first heard it on GTA.
Steven Ogg really tripped while recording the introduction to the mission Fresh Meat leading to a mostly improvised scene (Franklin's laughter, Trevor's rant).
In a more serious example, Madrazo's actor Alfredo Huereca miscalculated his swing with a soft bat during the mission Marriage Counselling and managed to hit Ned Luke in the elbow with the wooden part of it. This take is used in the final version of the game, making Michael's reaction real.
Considering there are a number of easter eggs in this game, it's no surprise some people are going nuts over rumors. One big, confusing thing at the top of Mount Chilead is a diagram showing what looks like a flying saucer, an underground network of tunnels inside the mountain, and a pictogram of what looks like a man with a jetpack. Cue hordes of people poring over every clue imaginable to try to find a hidden jetpack item (the most popular thing people have been missing since San Andreas).
It was often believed that you could manipulate the stock market outside of specific missions by blowing up property belonging to one company, causing their stocks to fall and their competitor's to rise. This is not true, and was likely started by the assassination missions having a similar system.
In the "Beta Code" for the Option C ending, it originally was not going to be the Golden Ending. It was originally going to be a "Kill Franklin" ending, with the player assuming the role of Lamar who had to do the task.
In 2012, a radio station called Nightride FM was announced by Kavinsky on his Twitter, and was stated to be hosted by him. It seems to have been completely cut and is not even mentioned in the final game - or Kavinsky lied about it ever existing.
Vinewood Boulevard Radio was originally going to be "P.M.R", a 90's rock station similar to Radio X in San Andreas, and hosted by Trent Reznor. It was cut and replaced with the modern rock station we have in the final version, but this change seems to have been a late one as the P.M.R station logo is still in the game files.
Worldwide FM was a jazz station before it became a world music one. This and the above example are referred to in the game files as "Jazz" and "90's Rock" stations respectively.
Brucie Kibbutz was originally supposed to have a slightly larger role in the game, as one of the targets in Devin Weston's car theft ring. While most references to that mission have been removed, the car the player was originally supposed to steal (a red vintage Stinger convertible) is present as the sixth car on the Packer in "Pack Man", despite Devin only asking for five cars.
There was going to be a heist called "The Sharmoota Job" that would have involved a "nice house" and stealing a safe, a horse and someone's wife. It would have involved Michael and Trevor and have three options for how it would have been performed. In the final game this is reduced to Trevor kidnapping Madrazo's wife off-screen, with Michael being unhappy about it when he finds out, partly because the horse riding mechanism from Red Dead Redemption couldn't be implemented into the game.
Similarly, the Paleto Score had a second option that was abandoned.
Based on the amount of available combat and hijacking vocals for NPCs in the game, it's safe to guess that the online player characters were once planned to be voiced.