I always laugh to myself when people, in attemping to explain away Bible contradictions chalk it up to a "copyist error." Well guess what? A copyist error is still error! Error in a supposedly infallible book! Or would you have me believe that the God who went to so much trouble to inspire a book so vital to our salvation, didn't bother to preserve it free from corruption?
It's true that for every contradiction you find in the Bible there's an eager apologist falling all over him/herself to show you why it's actually not contradictory. (The manner of Judas' death, for example.) But here's two that, for me at least, are indisputable:
Matthew 27:9,10: "Then that which was spoken through Jeremiah the prophet was fulfilled: And they took the thiry pieces of silver, the price of the one whose price had been set by the sons of Israel; and they gave them for the potter's field, as the Lord directed me."
But this is a quote from Zechariah, not Jeremiah. Nothing about "30 pieces of silver" is found in all of Jeremiah. Apologists like to reason that Matthew was partially quoting Jeremiah too in this passage, but the claim doesn't hold water. The closest reference is an account in Jeremiah 32 that speaks of Jeremiah buying a field at Anathoth for 17 shekels of silver (not thirty). However the context shows that this was to prophetically illustrate that, following the period of Babylonian captivity, "Houses and fields and vineyards will again be bought in this land." It had nothing to do with the burial of a betrayer. And it wasn't called the "Potter's field" either.
The other one is found in the gospel of John. The three synoptic gospels (Matthew, Mark, Luke) all say that Jesus was crucified after eating the Passover with his disciples. (See Mark 14:14 for example.) But I was shocked to realize that in John's gospel, Jesus dies before the Passover meal, not after.
In John 13 we see Jesus having a meal with his disciples, yet it is nowhere referred to as the Passover. In fact John 13:1 places this event "before the Feast of the Passover." Later on in chapter 19, Jesus is before Pilate. John 19:14 says "Now it was the day of preparation for the Passover; it was about the sixth hour. And he said to the Jews, 'Behold, your King!'" Yes, here we see Jesus executed on the "day of preparation for the Passover," that is to say, before the Passover had happened!
At this point apologists will try to play word games to try and show how the phrase "day of preparation for the Passover" surely must mean something other than what a casual reading would suggest. But there's one other verse that, for me, is the clincher. If we back up a bit to John 18:28 we read: "Then they led Jesus from Caiphas into the Praetorium, and it was early; and they themselves did not enter into the Praetorium so that they would not be defiled, but might eat the Passover."
To this I ask, "Why were the Jews worried about being unable to eat the Passover, when (according to the other three gospels) they supposedly ate it not twelve hours earlier?" It seems clear to me that, according to John, at the time of Jesus' death the Passover was a then-future event.