Contradiction with Isaiah 54:17
Isaiah 54:17 promises protection and that no weapon formed against God's people shall prosper, whereas Isaiah 21:10 describes the destruction and trampling of God's people.
Isaiah 54:17: No weapon that is formed against thee shall prosper; and every tongue [that] shall rise against thee in judgment thou shalt condemn. This [is] the heritage of the servants of the LORD, and their righteousness [is] of me, saith the LORD.
Contradiction with Jeremiah 29:11
Jeremiah 29:11 speaks of plans for welfare and not for evil, to give a future and hope, which contradicts the imagery of judgment and destruction in Isaiah 21:10.
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]
Contradiction with Psalm 91:7
Psalm 91:7 suggests divine protection with thousands falling around but not touching the faithful, while Isaiah 21:10 describes the crushing of God's people.
Psalm 91:7: A thousand shall fall at thy side, and ten thousand at thy right hand; [but] it shall not come nigh thee.