Granted you don’t want any glaringly obvious real world errors to blast readers out of the fictional world you’ve written, but how exact do you have to be?
If your story is set in the ’60s then your characters don’t have smart phones. Simple, right?
Yesterday, I found myself hitting Google every other minute to check trivia like what year a certain cell phone model was released and what phone apps were available on that model. I got almost no actual writing done at all because I was entrenched in the minute details of “when”.
Really, is anyone going to read a book and think, “Oh, that movie came out in 2007 so there is no way those characters are watching that TV show, it only started in 2010.”
I sincerely hope not, because these details are killing me 🙂