When I read I constantly "check" with previous pages for clarification on what is written on latter pages (sometimes they don't agree)
As most of my fiction is historical drama I also like to stop and check on the internet for the accuracy of the points that the story is based upon
So reading for me is not a passive occupation, I have very good retention so it grates when the continuity is incomplete or plainly wrong
Some writers are meticulous with regard to the accuracy of the story, others are too lazy to care