The players signed identical contracts, according to Wilson. The players received a $10,000 signing bonus, a $10,000 workout bonus and $895,000 base salaries.
Arnold has played six games, totaling 10 tackles and one pass breakup.
Carter, who played three games for the Cowboys last season, made his Texans debut last week against the Chargers. He played 17 defensive snaps and three on special teams.