At the end of The Book of Eli, we the audience learn that
Eli is blind and has been the whole movie. We learn the secret when Carnegie first opens Eli's book and sees that it is written in Braille. But Solara was with Eli on Alcatraz at that point, so she never saw the Braille and may well not have known what it meant in any event. I saw no sign of that Solara ever learned of Eli's blindness but I may have missed something.
Did Solara ever learn Eli's secret?
EDIT: My assumption is that Eli recited the book and then died within a week, presumably of complications from his gunshot wound. 2 words per second for 16 hours a day gets the job done in one week, assuming an upper bound of 800,000 words in the King James Bible. So I don't think Eli and Solara spent enough time together on Alcatraz for his little mistakes to give him away.