But for every element of difference you introduce in a story, there will be a multitude of consequences rippling out from the point of difference. Utilize unintended consequences. No one can ever fully predict the results of their actions. The same is true of the people in your world. Sometimes people set out to do one thing, and effect something totally unexpected.
Unintended consequences are especially rife when talking about technological change.
Every piece of technology will eventually find niches other than what its developers intend. Beware of contradicting yourself. This is another way of saying you need to follow the rules you establish for your story. Contradictions are a more than simply saying that the planet Frozz has a 23 hour day on page 3 and a 32 hour day on page 15. It's possible to have elements of a story that contradict each other only implicitly.