The blog “God Didn’t Say That” has a useful discussion of three types of errors that occur in Biblical manuscripts.
We’re used to mass-produced Bibles printed by machines, so we forget the type of errors that are found in handwritten manuscripts. (Try, someday, to copy a page from the Bible by hand, and when you’re done, count the errors you made. Then take a moment to give thanks you only have to copy a single page.)
Generally speaking, these errors aren’t all that significant, because they occur in a few manuscripts (duplicates of an ancestral manuscript where the error first occurred) but not in others. The article is interesting, though, because it describes the different types of errors and discusses the different approaches that translators use to deal with them.