Zootopia is very firmly on topic, containing significant elements of science fiction.
Conceit/Setting
Ignoring the talking animals, the film itself is set in a futuristic world, complete with steampunk zeppelins. The city of Zootopia features impossible architecture (suggesting materials technology in advance of our own) as well as being arranged into differing environments that are dependent on currently impossible (or at least implausible) technology such as the rain dispensers in the Rainforest District and the truly enormous heat-exchanger walls that keep the Sahara Square area toasty and the Tundratown area frozen.
One of the central themes is that the police bunny must discover the cause of the disappearance of several predators who turn out to have been
given a fictional drug, making them revert to their savage pre-enlightened state.
Marketing
The film has been trailed as a 'what-if' world where humans (and indeed any form of primate) never existed. This places it quite firmly into the alternate reality category.
“Apes are too much like us, so as soon as we put them in the story,
everyone goes, oh the ape is the smart one. And we wanted all these
mammals to seem like more or less equal intelligence, more or less,”
said Byron Howard.
How Zootopia was made, talking with Disney’s animation team
Additionally, we see the process by which the animals were uplifted (through evolution) rather than simply being asked to accept that the animals talk as a matter of course
At the Natural History Museum at the end of the film, you’ll see
things like primitive jackelopes fending off sabertooth leopard. There
are big paintings of primative tribes of lions and zebra shaking
hands. It’s supposed to be the moment that they bonded at the watering
hold and declared peace. We used to have a scene where Bellweather
gives Judy a speech about the fountain and he looks outside and you can
see the fountain and town’s square is the watering hole where they
united in peace. We actually miss that scene because it gave a nice
history of Zootopia, but we didn’t have room for it.
ZOOTOPIA’S CREATORS TALK HIDDEN DISNEY GEMS AND CUT SCENES