So, you're writing a story. And it's set here on earth. And the genre is something other than fantasy or paranormal.
Then it's best to get every little fact right. (Fantasy and paranormal give you a little wiggle room).
A reader can be shoulder deep in suspending their disbelief, and they come across a fact, the smallest mention, even a seemingly insignificant detail, and they know it's wrong. It sucks them out of the story faster than you can say, "Well that isn't right!"
I read a book a couple of years ago, a fiction thriller. I bought it after reading a tweet full of praise for it. The author was a PhD. And the "Look Inside" feature on Amazon showed that the book had great potential.
It was a big book. Almost 700 pages. Lots of action that held me on the edge of my seat. It was hard to put down. Although there were consistent small typos, the story was so good I skimmed right over mistakes. I kept thinking, this guy is a genius; the things he knows about! Each time his character delved into highly technical stuff, I thought about how much work the author must have gone to, to write it.
Weapons, vehicles, helicopters, geography, medicine, governments, the list went on and on.
It was so good, I even tweeted to the author that the pages were on fire; I couldn't turn them fast enough.
As I read, I kept thinking about the review I would leave. In all fairness, I knew I had to make mention about the typos or actual spelling errors.
And then, almost at the end of the book...it happened.
I read something that I knew was flat out wrong. If the author had taken ten or fifteen minutes to Google it, he'd have known it was wrong, too. But he didn't. And that was enough that I lost all confidence in his facts being right.
I opted not to leave a review... over a small detail that had cast doubt over everything I'd once thought the author a genius for.
When you write fantasy and paranormal, yep, magical things happen. The laws of physics can even bend via magic. But if you're writing something that could not occur here on earth--and you're doing it in a genre that leaves no squirm room, you'd best get it right. :-)