Accuracy in fiction is defined by reality, the reality of the story not the reality of the world we live in. But the lines are blurred. An article I read many years ago, in one of the writers magazines, stated that a story set in Manhattan was ruined because someone turned left on Fifth Avenue and drove uptown. People who have spent any time in New York know that Fifth Avenue is one-way, downtown. Now that the internet is available little facts such as that one are easier to check, but, as the onslaught of political pundits has shown us, people love to speak with authority even when they are unsure of the facts. Writers have to be careful that the information they find is correct.
The context of the story is what matters when determining if a fact is accurate or not. If in that Manhattan story some crime mob had changed the signs on Fifth Avenue so they now pointed uptown, then that left turn might have been acceptable. This is the reason that readers disparaging remarks such as dragons can't fly that fast or aliens can't teleport through a black hole can be legitimate criticism if the story establishes a fact then ignores it. Yet there is more to the context of a story as it relates to accuracy than facts established within its pages. There's also the tone and what the writer has shown to be important.
I'm currently listening to an audio of Bel Canto by Ann Patchett. This is the story of a terrorist takeover of a birthday party in an unnamed third world country. It has a number of events that seem unreasonable or just wrong—air conditioning ducts in a residential home that are big enough for people to crawl through and a telephone call to someone who states he's just come home for lunch when it has already been established that it is late enough to be getting dark outside. Yet this book is not about the portrayal of an accurate terrorist event. It's about love, loyalty, gender relationships, the love of art, and what is valuable in life. The setting is just an event that slows a group of type A people down long enough to allow them to reflect on their lives. Because of that these small facts are insignificant.