Contradiction with Exodus 20:25
This verse contradicts Joshua 8:30 as it instructs not to build altars with hewn stone, whereas Joshua 8:30 involves an altar with whole stones.
Exodus 20:25: And if thou wilt make me an altar of stone, thou shalt not build it of hewn stone: for if thou lift up thy tool upon it, thou hast polluted it. [build...: Heb. build them with hewing]
Contradiction with Deuteronomy 27:5-6
While Joshua 8:30 reflects this commandment by using whole stones, it contradicts the earlier instruction in Exodus about using plain earth for altars.
Deuteronomy 27:5-6: And there shalt thou build an altar unto the LORD thy God, an altar of stones: thou shalt not lift up [any] iron [tool] upon them.