Looks like 1940s

It certainly gives the film a lot of character

I watched this in black and white. It gave it a nice feel of the 1940's.

Retro futuristic feel like with TAS and the Arkham games.

It's set in Gotham City. A FICTIONAL CITY.

It doesn't have to be realistic , its not even a real city.

To me it looks more early 1980's based off the cars you see in the background.

It can't be underestimated just how much Blade Runner, and to a lesser extent, Terry Gilliam's Brazil had on filmmakers and pop culture in general.

And both of them while having advanced technology, still had some old-fashioned cars, people wearing trenchcoats and trilbys, and art deco like 1940's film noir.

Tim Burton's Gotham is the same. Batman '89 is still my favourite depiction of the city. I love it.

Be having like Metropolis looking like the 40s with the clothing, buildings and cars.