Contradiction with Acts 1:13
It mentions "James the son of Alphaeus" and "Judas the brother of James" as apostles not explicitly sent by Jesus, whereas Colossians 1:1 implies Paul’s apostleship is by the will of God.
Acts 1:13: And when they were come in, they went up into an upper room, where abode both Peter, and James, and John, and Andrew, Philip, and Thomas, Bartholomew, and Matthew, James [the son] of Alphaeus, and Simon Zelotes, and Judas [the brother] of James.
Contradiction with Galatians 1:1
States that Paul is an apostle not of men nor by man, but by Jesus Christ and God the Father, while Colossians 1:1 simply references his apostleship by the will of God.
Galatians 1:1: Paul, an apostle, (not of men, neither by man, but by Jesus Christ, and God the Father, who raised him from the dead;)
Contradiction with 1 Corinthians 1:1
Paul is called an apostle by the will of God, similar to Colossians 1:1; this sameness could be seen as a contradiction of uniqueness.
1 Corinthians 1:1: Paul, called [to be] an apostle of Jesus Christ through the will of God, and Sosthenes [our] brother,