This Bible contradiction is from the Skeptic's Annotated Bible.
Matthew 27:28 View context
And they stripped him, and put on him a scarlet robe.
Mark 15:17 View context
And they clothed him with purple, and platted a crown of thorns, and put it about his [head],
John 19:2 View context
And the soldiers platted a crown of thorns, and put [it] on his head, and they put on him a purple robe,