Contradiction with John 18:20
Jesus tells the high priest that He always spoke openly to the world, contradicting the idea of silence or secrecy implied by the high priest's question in Mark 14:60.
John 18:20: Jesus answered him, I spake openly to the world; I ever taught in the synagogue, and in the temple, whither the Jews always resort; and in secret have I said nothing.
Contradiction with Isaiah 53:7
This verse describes the Messiah as silent before His accusers, which contrasts with the implied expectation in Mark 14:60 for Jesus to answer.
Isaiah 53:7: He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth.