This Bible contradiction is from the Skeptic's Annotated Bible.
After noon on the day before the Passover meal
John 18:28 View context
Then led they Jesus from Caiaphas unto the hall of judgment: and it was early; and they themselves went not into the judgment hall, lest they should be defiled; but that they might eat the passover.
John 19:14-16 View context
And it was the preparation of the passover, and about the sixth hour: and he saith unto the Jews, Behold your King!
But they cried out, Away with [him], away with [him], crucify him. Pilate saith unto them, Shall I crucify your King? The chief priests answered, We have no king but Caesar.
Then delivered he him therefore unto them to be crucified. And they took Jesus, and led [him] away.
Mid-morning on the day after the Passover meal
Mark 14:12 View context
And the first day of unleavened bread, when they killed the passover, his disciples said unto him, Where wilt thou that we go and prepare that thou mayest eat the passover?
Mark 15:25 View context
And it was the third hour, and they crucified him.