Time to talk about technology.
No, I couldn't resist the alliteration.
One of the challenges of writing contemporary fantasy is that technology is always changing, especially with regards to the internet and connectivity. These days, it seems the majority of the people can operate their phones as if they were miniature computers, playing games, pulling up maps or websites ... the list goes on. (I am not one of those people. My phone makes calls, period. I have been known to (rarely) take pictures with it, but that's why I have a digital camera.) This capacity only seems to keep expanding, so unless the characters are luddites, trapped in a blackout (hi, Revolution!), their magic interferes with the workings of technology (come to think of it, that may be why I've never noticed any discrepancies with the Dresden Files) or the absence of technology is in some way a plot point ... most writers will have to deal with it.
It's a problem made worse by the fact that it may take a year or more to write and then polish a novel (though arguably, you can make the necessary updates during this time), and unless you're lucky and have an agent, possibly a couple of years to find a home and another few to go from acceptance to publication. What if something comes up in the interim that actually invalidates a plot point?
I have no solution for this except to weather the storm - or to visibly set your story in a particular year. With Flow, the novel had initially been written with the intent that it was set in 2007. After it was accepted, I debated for a bit and decided to leave it. So modern readers may find the mobile disconnect a trifle odd: Kit's cellphone is just a phone; Hadrian does his research from a laptop; and there is, wonder of wonders, a single reference to a pay-phone. (Grant that it's in an old diner along the road which might even still have such a device today. Maybe.)
Sure, science fiction has to put up with this, as well, but it's more likely to be on the order of after the book has been published - five, ten years down the line. I actually dealt with this in Scylla and Charybdis - again with connectivity - and created a mental scenario, never explicitly discussed in the book, where society actually moved away from our current constant connectivity culture and then gradually back. In one city the characters visit, being disconnected is considered a sign of personal freedom.
One of my favorite stories about the evolution of science and science fiction comes from reading Connie Willis and Cynthia Felice's Water Witch. It's more of a science fantasy than straight science fiction, at least in tone and influences, and despite having been published in 1982, it has aged very well - perhaps because the story is more focused on the characters, the politics, and the ritual.
However, near the end of the book, there's a reference to a city that is disconnected from the rest of the world because it's not physically possible to run wires for communications across the distance. I put the book down and giggled. ... then I picked it back up and finished it, but it's astonishing what we assume is impossible.