Contradiction with Acts 10:28
Here, Peter mentions it is unlawful for a Jew to associate with or visit a Gentile, but Acts 11:11 describes the Spirit directing Peter's interaction with Gentiles.
Acts 10:28: And he said unto them, Ye know how that it is an unlawful thing for a man that is a Jew to keep company, or come unto one of another nation; but God hath shewed me that I should not call any man common or unclean.
Contradiction with Matthew 10:5
Jesus instructs his disciples not to go to the Gentiles, while in Acts 11:11, Peter is led to welcome the Gentiles.
Matthew 10:5: 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 Galatians 2:12
Peter is criticized by Paul for withdrawing from Gentiles, whereas Acts 11:11 shows Peter engaging with them.
Galatians 2:12: For before that certain came from James, he did eat with the Gentiles: but when they were come, he withdrew and separated himself, fearing them which were of the circumcision.
Contradiction with Deuteronomy 7:3-4
The Old Testament law advises against associations with other nations, but Peter's action in Acts 11:11 is contrary to this.
Deuteronomy 7:3-4: Neither shalt thou make marriages with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son.
Contradiction with Ezra 9:12
Israelites are instructed not to seek the peace or prosperity of other nations forever, which differs from the acceptance shown in Acts 11:11.
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.