This glitch takes you to Central Park in an early state. This might be an area that will be added later on in DLC.
Step 1: STARTING POINT
You start off in the Hell's Kitchen district and walk to the very left of 42nd street. There's a gate with a truck in front of it that you can glitch through using the cover that's behind it. You have to be positioned in a certain spot and keep pressing B or Circle depending on where you play. If you use the position from the video it shouldn't be too difficult.
Now you're already outside the playable map, but it seems to be pretty much finished and populated with a couple civilians. From here, make your way north to 46th street and look for some red flairs and a military gate.
Step 2: THE HARD PART (WALL GLITCH)
This will be the most frustrating part and it can take a while, but if you keep trying this will work out. You need the ballistic shield and the mobile cover from the security section for this part. Place the cover in the left corner of the gate with your back turned to the wall. Place it very close to yourself so you are trapped in there.
Now equip your shield and keep rolling backwards until you get pushed through the wall behind you. I spent about 15 minutes myself here until i got it right. Try out different angles and different positions and you should get it after a while.
Step 3: LAST WALL GLITCH (EASY)
Once you've made it , you have to go through one last wall, but this one is fairly easy. use the same strategy as you did just now and push yourself through. That's it guys, it will definitely take some patience but if you have patience you will get there.
Step 4: LAST BIT TO CENTRAL PARK
If you want to get to Central Park directly without exploring the area, go straight ahead to the freeway that's loaded with cars. You can get on it by climbing the truck that's blocking the way.
Take the bridge all the way to the end so you're in the unfinished area of the map. Follow the roads north-west to find the Central Park.