Thinking of textual blunders, an example ocurred to me: Matt 27.
The gospel-we-know-as-Matthew's narrative about the downfall of Judas Iscariot contains an error:
"There was fulfilled that which was spoken by Jeremy the prophet, saying, And they took the thirty pieces of silver, the price of him that was valued, whom they of the children of Israel did value; And gave them for the potter's field, as the Lord appointed me."
Jeremiah never said anything about thirty pieces of silver. Some folks have tried to epicycle Jer.18:2–3 into something, but it's fair to say that the author of Matthew just plainly made a mistake. The citation is instead a paraphrase of Zech.11:13.
This from the most outwardly 'Jewish' gospel.
The more I think about it, the more I doubt that the gospel writers were the early Jewish-Messianists that people think they were.
I'm trying to figure out why the Hellenists would co-opt the mantle of Judaism after the fall of Jerusalem, though. The remnants of the Pharisees must have been furious at these Paulinists, who were claiming to be the New Jerusalem. I can only imagine.