I'm actually playing Vice City, and I can't believe how a game developped in 9 months, 12 years ago, can be such a vast experience. Anyway, this thread was made for GTA V, and I don't see any reason why we couldn't do the same with Vice City :
1) You certainly know that Tommy can be a taxi driver during his free time, but did you know that he could also be a bus driver ? If you steal a Coach, you can pick up pedestrians waiting at bus stops, and you'll earn 5$ for each passenger delivered.
2) The (awesome) song "La Vida Es Una Lenteja", that you can listen on Espantoso, or Inside the Ocean View Hotel lobby was actually made by R*. The funny stuff, is that if you listen VERY closely to the song, you'll hear little sounds used during normal gameplay (for exemple, the "cheat code activate" sound is used as percussion).
3) House models in Little Havana (and also in the cul de sac near Well Stacked Pizza in Vice Point) are totally disproportioned. These are about twice the size they should be, just put Tommy in front of the door to see it. Oddly, the same house models used in Little Haiti are well proportioned.