No idea how they managed to get up there without running into security on the ground floor who would have most likely stopped them (its a business tower so there are never any kids there). The scene before they get to the roof they show an elevator ride going past floor 46, but those elevators don’t get up all the way to the top. My office is on the 46th floor and to get to Alghanim offices which are on the 70th floor, I need to take two different elevators down to the ground floor and then 2 more different elevators on the other side past security back up to the 70th. Not only did they manage to bypass all the security and figure out the elevator maze, but they eventually got to the roof and then dangerously started sliding around. Disturbing.
Thanks Dal