Contradiction with Exodus 14:13
Exodus 14:13 speaks of God's deliverance and salvation from enemies, while Isaiah 21:2 speaks of treachery and destruction coming upon a nation.
Exodus 14:13: And Moses said unto the people, Fear ye not, stand still, and see the salvation of the LORD, which he will shew to you to day: for the Egyptians whom ye have seen to day, ye shall see them again no more for ever. [for the...: or, for whereas ye have seen the Egyptians to day]
Contradiction with Psalm 18:2
Psalm 18:2 emphasizes God as a source of safety and refuge, in contrast to Isaiah 21:2's depiction of imminent threat and betrayal.
Psalm 18:2: The LORD [is] my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, [and] my high tower. [my strength: Heb. my rock]
Contradiction with Matthew 5:9
Matthew 5:9 blesses peacemakers, which opposes the call for devastation and betrayal seen in Isaiah 21:2.
Matthew 5:9: Blessed [are] the peacemakers: for they shall be called the children of God.
Contradiction with Isaiah 9:6
Isaiah 9:6 speaks of peace and righteous governance through the coming of the Messiah, contrary to the betrayal and chaos described in Isaiah 21:2.
Isaiah 9:6: For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.
Contradiction with Jeremiah 29:11
Jeremiah 29:11 promises plans for peace and hope, which contrasts with the violence and treachery mentioned in Isaiah 21:2.
Jeremiah 29:11: For I know the thoughts that I think toward you, saith the LORD, thoughts of peace, and not of evil, to give you an expected end. [expected...: Heb. end and expectation]