There are hazards to writing something that takes place in the real world, things I didn't even think about when I started plotting my current book. I'm used to being able to make up everything - to come up with the way the world works, how far away one place is from another, and anything else the story needs.
It's one thing to create a world. It's something very different to have to get a pre-existing world right.
For instance, last week I bugged a co-worker who's an avid hunter about guns. One of the book's characters decides dealing with demons up close is a bad idea, and learns how to use a rifle. I kept the details deliberately vague, as I figured I could edit in what I needed later. The info I got from my co-worker was interesting; he not only listed a good 'starter' rifle someone would learn with, but gave me a full description of the second gun the character ends up getting, complete with the fact that it has a 300-yard range and can take down an elk.
It's the little details that matter.
There are a ton of things I still have to look up, and much like the gun details, I expect to edit them in later. Things like hotel floor plans, roads in major cities and small towns, and actual maps of those places so I can make sure Our Heroes' travels are accurate. I plan to make full use of Google, maps and street views and all that, and hope I can find a place that actually fits what I've written. Sure, anything can be fixed in editing, but still.
All in all, having to take all this into account has been an interesting experience. This isn't something I worry about in most of my writing. True, the book I wrote last year took place on Earth, but it was almost entirely at a college campus, which is its own kind of fictional. And before that, it had been years since I wrote something that took place in the real world, and that was over half a century after a major change to the world so I had plenty of room to improvise.
As for fixing all of this in editing, that's another point. I'm not as excited about writing this book as I thought I would be. It feels a bit like it's all been done before - no real surprise, as this is my third time trying to tell this story. I also might be suffering from Shiny New Project Syndrome; the things I still have in the plotting stages seem a lot more interesting. But I'm going to finish this book, one way or another.
The last thing I need to know is if I can well and truly make this story work. And I won't know that until it's done.