Contradiction with Matthew 10:5-6
Jesus instructed his disciples not to go to the Gentiles or Samaritans, whereas in Acts 10:33, Cornelius, a Gentile, is prepared to hear Peter.
Matthew 10:5-6: These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into [any] city of the Samaritans enter ye not:
Contradiction with Deuteronomy 7:2
Commanded Israelites to destroy other nations and make no covenant, whereas in Acts 10:33, Peter goes to meet a Gentile.
Deuteronomy 7:2: And when the LORD thy God shall deliver them before thee; thou shalt smite them, [and] utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them:
Contradiction with Exodus 23:32
Warns against making covenants with foreigners, while Acts 10:33 demonstrates openness to a Gentile.
Exodus 23:32: Thou shalt make no covenant with them, nor with their gods.
Contradiction with Ezra 9:12
Advises against seeking the peace or prosperity of other nations, contrary to the willingness to engage with Cornelius in Acts 10:33.
Ezra 9:12: Now therefore give not your daughters unto their sons, neither take their daughters unto your sons, nor seek their peace or their wealth for ever: that ye may be strong, and eat the good of the land, and leave [it] for an inheritance to your children for ever.
Contradiction with Nehemiah 13:3
Separated Israelites from mixed multitude, whereas Acts 10:33 shows inclusion of Gentiles.
Nehemiah 13:3: Now it came to pass, when they had heard the law, that they separated from Israel all the mixed multitude.