Probably the most interesting bit is that in this particular universe,
Metropolis and Gotham are across the river from each other, giving them a New York/Jersey City-type relationship. Generally Metropolis and Gotham have a bit more distance, being located in Delaware and New Jersey respectively. According to the maps, you can even take a ferry between the cities.
The Turkish Airlines ads also mention that Gotham has shaken off its past, implying that things have been quiet on the supervillain front in the city for a while. Reinforcing that, Bruce Wayne seems to be more interested, at least in the ad, in civic boosterism as opposed to punching bank robbers. Equally interesting is that Lex Luthor appears to have swooped in and taken over Metropolis; while the website doesn’t quite outright say it, it’s pretty clear Lex paid for the city to be rebuilt.
There are also a few Easter Eggs if you know your DC Comics.
The Gotham page references Neo-Eden, a favored hideout of Poison Ivy, for example, and DC’s fictional prison Stryker’s Island, where Supes tends to dump the weirdos he fights, sits equidistant between the two cities. There’s also little nods here and there to comics history. Apparently
in the DC Cinematic Universe, Jerry Siegel and Joe Shuster became music promoters, not comics creators, and
they both have music venues, and in Gotham, Neal Adams became a shipping magnate with a port named after him. There’s even a subtle nod to the Joker, referencing Amusement Mile in Gotham and its “dark carnival” atmosphere