Apples and Peas
There are no limits to what an author can create, but it's important that the environment, characters, and behaviors are governed by a set of rules.
A wonderful editor just looked at my latest novel and pointed out a continuity problem. One of my characters was picking apples and peas in the garden. Problem! Apples are not ripe at the same time as peas. I changed peas to carrots-(the character likes them, too).
If you're a writer, remember all the details in your story. Write them down and keep them consistent; this includes weather, seasons, and what can take place in both.
For me, changing peas to carrots did not disrupt my story, but keeping apples and peas together did make my reader question the scene.
The best stories are when the worlds created, fantastical or real, can be seamlessly imagined. This happens in the comfort of some rules.