Dr Jay and Al Fadi discuss the refutations to Dan Brubaker book: Corrections in Early Quranic Manuscripts.  one of the refutations is by  Hythem Sidky who writes a book responding to Dan's book.  Dr Jay and Al Fadi also talk about the historical problems of the Quran, they give an example from Sura 20 : 85-87,95-97,  where it talks about a Samaritan who lived in the time of Moses and helped the Israelites build the golden calf.  The problem with that story is the time period ; Moses lived in 1400 BC and the Samaritan did not exist until 722BC. In conclusion; having even one mistake in the Quran proves that is not divinely preserved.