There is only one passage in the Gospels that was added hundreds of years later--it's
John 7:53-
8:12, the story of the woman caught in adultery (where Jesus says, "let he who is without sin cast the first stone"). However, even though this was added to the
Gospel of John at a late date, the story itself dates back at least to 150 AD and probably earlier. (See
Raymond Brown's book on John in the
Anchor Bible Commentary for more details).