Contradiction with Exodus 12:48
Joshua 5:8 describes the circumcision of the Israelites born in the wilderness before entering Canaan, which contradicts Exodus 12:48, where all males must be circumcised to participate in Passover, implying they should have already been circumcised.
Exodus 12:48: And when a stranger shall sojourn with thee, and will keep the passover to the LORD, let all his males be circumcised, and then let him come near and keep it; and he shall be as one that is born in the land: for no uncircumcised person shall eat thereof.
Contradiction with Genesis 17:10-14
Joshua 5:8 shows a mass circumcision event needed before entering the Promised Land, whereas Genesis 17:10-14 commands circumcision on the eighth day after birth, suggesting they were not following this covenant.
Genesis 17:10-14: This [is] my covenant, which ye shall keep, between me and you and thy seed after thee; Every man child among you shall be circumcised.