The first few seasons of Batman:TAS were a little inconsistent with technology. The TVs were still in black & white, but Bruce also watched black & white TV as a kid. In real life, it only took about a decade for TV to get color. There were modern and futuristic computers everywhere and the Riddler's maze video game looked like something for an Atari, but this series was airing when I was playing the Genesis and SNES in real life. The cars looked like they came from the 1940's, and I'd say the style of dress for people of Gotham lined up with the 40's and 50's as well. Then there was that episode where Harley Quinn was out on parole, and her style was more modern/90's.
Don't get me wrong, it totally worked for the show. It's just that Gotham existed in a time all its own.