Blimp: many players think the blimp in GTA V is only available in the last GTA, but actually, it was added by first time in GTA Vice City. The only variable was that in GTA VC, the Blimp was an object in the sky without collision but in GTA V, the blimp is a driveable aircraft.
In-Air Car Control: When a lot of players used by first time this feature, they never remember that this was a feature presented in GTA SA; there were only a few changes between the original and the new version, in the original version you just can do one movement in the air but in the new version you can do whatever you want before you touch the ground. Try it and you´ll see what I´m talking about!
Freefall: Well, in GTA V this feature can be specially used via cheat but also can be used when you falls down from an aircraft. But some players don´t know this feature was presented by first time in GTA IV & EfLC; the only change was the use of a mixture with ragdoll settings and animations.
Animals: GTA IV was the first game of the saga with interactive animals, the pigeons (flying rats); but GTA V was the first game with lots of interactive animals, such as pigs, dogs, cougars, cows, deers & sharks. (in the 3D era we got a sort of animals that are actually part of the map, like the submarine life in GTA SA or the flying birds that share their textures with the clouds).
Petrolcaps: some users noticed that in GTA V we can't shoot to the cars on their petrolcap because they just don't have one but the truth is, this is (as most of the features of the games) a feature of the previous game, GTA IV; I'm not sure if this is a bug, a mistake by the creators or simply an unrealistic feature.
Crash Damage on Walls: a few days ago I was playing GTA Online with a friend and he said "oh look! the walls suffer damage when you hit them, I'm sure is the first GTA that has that!" so I said, "yeah, but that's a previous GTA feature, they keep using it because is great".
Lazlow: yeah, some people think Lazlow, the character in the GTA V history mode, is a new character, but he has been in the GTA series for quite a while, since the 3D era; the only difference from previous appearances is that in GTA V is the first time he actually appears in person, in the previous times we can only hear his voice (like in the GTA IV add in the radio). (This is caused because Lazlow is a real person, he is one of the creators of the GTA series).