Callahan has been named the offensive coordinator/offensive line coach. Henderson is the secondary coach.
The Callahan move is interesting because he replaced long-time assistant coach Hudson Houck, who retired this week. Callahan was named the offensive coordinator but it's not known if he'll call plays, something Jason Garrett has done since joining the Cowboys.
Houck was the running game coordinator and Garrett's brother, John, was the tight ends coach/passing game coordinator.
Henderson, who replaces Dave Campo, spent the last three seasons with the Cleveland Browns.