I've been noticing with each DLC the game acts somewhat different, making new things possible and impossible. As someone still getting through the game, here are the few things I've noticed. Feel free to bring up any you've noticed.
Dogs. There's more than one model now. The dogs seemed to all use the chop model originally. Now there are more kinds around. This could make it harder to notice an out of place quadraped.
The army has different response time at Zancudo and it is easier to get in and take something now than when it was unpatched.
They broke then fixed the fire hose. Maybe it's important for something other than just the obvious fooling around with it...
The jetpack files found in 1.12 are worth mentioning.
Dunno if it's new, but I saw a Laser on patrol around Zancudo. It wasn't overtly hostile, just doing what most of us do with a nice fast plane and going on a canyon run. I didn't notice it before.
I will have more as I find it.