Contradiction with Joshua 10:40
Joshua 10:40 states that Joshua conquered the whole land, leaving none remaining, in contrast to Judges 1:9, which describes Judah fighting further battles in the land they were supposedly already given.
Joshua 10:40: So Joshua smote all the country of the hills, and of the south, and of the vale, and of the springs, and all their kings: he left none remaining, but utterly destroyed all that breathed, as the LORD God of Israel commanded.
Contradiction with Joshua 11:23
Joshua 11:23 indicates that Joshua took the whole land and gave it as an inheritance to Israel, suggesting there should be no need for further battles as in Judges 1:9.
Joshua 11:23: So Joshua took the whole land, according to all that the LORD said unto Moses; and Joshua gave it for an inheritance unto Israel according to their divisions by their tribes. And the land rested from war.
Contradiction with Joshua 21:43-45
These verses affirm that the Lord gave Israel all the land He had sworn to give to their fathers, and they had rest from war, contradicting the ongoing conquests described in Judges 1:9.
Joshua 21:43-45: And the LORD gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein.