Contradiction with 1 Samuel 30:18-19
These verses explain how David recovered everything that the Amalekites had taken and nothing was missing, contradicting any notion in 1 Samuel 30:16 that some spoil might not be retrieved.
1 Samuel 30:18-19: And David recovered all that the Amalekites had carried away: and David rescued his two wives.
Contradiction with Exodus 17:14
God commands Moses to write a memorial that He will utterly blot out the remembrance of Amalek, contradicting the scene in 1 Samuel 30:16 where the Amalekites are victorious temporarily.
Exodus 17:14: And the LORD said unto Moses, Write this [for] a memorial in a book, and rehearse [it] in the ears of Joshua: for I will utterly put out the remembrance of Amalek from under heaven.
Contradiction with Deuteronomy 25:19
God commands Israel to blot out Amalek from under heaven and not forget, contradicting their thriving presence in 1 Samuel 30:16.
Deuteronomy 25:19: Therefore it shall be, when the LORD thy God hath given thee rest from all thine enemies round about, in the land which the LORD thy God giveth thee [for] an inheritance to possess it, [that] thou shalt blot out the remembrance of Amalek from under heaven; thou shalt not forget [it].
Contradiction with 1 Samuel 15:3
God commands Saul to utterly destroy the Amalekites, contradicting their survival and activity in 1 Samuel 30:16.
1 Samuel 15:3: Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.
Contradiction with 1 Samuel 15:20
Saul claims to have obeyed God's command to destroy the Amalekites, yet 1 Samuel 30:16 depicts them as a thriving force.
1 Samuel 15:20: And Saul said unto Samuel, Yea, I have obeyed the voice of the LORD, and have gone the way which the LORD sent me, and have brought Agag the king of Amalek, and have utterly destroyed the Amalekites.