This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

Scarlet.

Matthew 27:28 View context

And they stripped him, and put on him a scarlet robe.

Purple.

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,