Contradiction with Matthew 5:39
Mark 12:4 speaks of violence against the servants, while Matthew 5:39 advises turning the other cheek in the face of violence.
Matthew 5:39: But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.
Contradiction with Romans 12:19
Mark 12:4 describes an act of vengeance against the servants, whereas Romans 12:19 urges believers to leave vengeance to God.
Romans 12:19: Dearly beloved, avenge not yourselves, but [rather] give place unto wrath: for it is written, Vengeance [is] mine; I will repay, saith the Lord.