Contradiction with 1 Samuel 31:4-5
These verses suggest that Saul's death was by suicide whereas 1 Samuel 31:2 covers the death of his sons, possibly implying a different context or order of events.
1 Samuel 31:4-5: Then said Saul unto his armourbearer, Draw thy sword, and thrust me through therewith; lest these uncircumcised come and thrust me through, and abuse me. But his armourbearer would not; for he was sore afraid. Therefore Saul took a sword, and fell upon it. [abuse...: or, mock me]
Contradiction with 2 Samuel 1:6-10
This passage suggests that an Amalekite killed Saul, contradicting the implication that he died along with his sons in battle.
2 Samuel 1:6-10: And the young man that told him said, As I happened by chance upon mount Gilboa, behold, Saul leaned upon his spear; and, lo, the chariots and horsemen followed hard after him.