The movie was quite powerful, huh?
The white towel scene and the washing the floor with Christ's spilled blood is not in the Bible. I thought it was touching though, expecially with the flashback of Mary Magdeline about to be stoned!
I liked how Mel added some things not specifically outlines in scripture to show the humanity of Jesus or the feelings of those close to him.
BTW - just because it is not in Bible doesn't make it wrong. Remember, in the book of John it is said that all of the books in the world could not contain the works Jesus did while on earth.