Development cost for GTA 5 was a whopping $137 million, not including the marketing budget which was nearly the same! This price tag makes it one of the most expensive games ever created. Despite the high cost, it was a great investment as GTA 5 is also one of the best-selling games of all time.
Voice actors for the three main characters, Franklin, Michael, and Trevor, all went through physical transformations to better embody their roles. Shawn Fonteno (Franklin) gained muscle, Ned Luke (Michael) lost weight, and Steven Ogg (Trevor) reportedly grew out his beard and mustache and stopped cutting his hair for months on end.
A couple of celebrities sued Rockstar Games over their likeness being used in GTA 5. Lindsay Lohan unsuccessfully sued over the character Lacey Jonas, and likeness rights were blurred in the case of Danny McBride and the character of Jay Norris.
The stock market in GTA 5 is actually a complex and functional system. The prices of stocks fluctuate based on in-game events, allowing players to make (or lose) a lot of money depending on their investments.
When GTA 5 was re-released for newer consoles, some content had to be altered or removed due to changes in cultural norms. For example, torture scenes were toned down and the ability to buy clothing with profanity was removed.
There are rumors of conspiracy theorists who believe that the clouds in GTA 5 sometimes form messages that hint at future downloadable content (DLC). Rockstar has never confirmed this, but it's a fun detail for players to look out for.