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.
Callahan spent the last four seasons as the assistant head coach/offensive line coach with the New York Jets and has been a former head coach, leading the Oakland Raiders to Super Bowl XXXVI.
Henderson, who replaces Dave Campo, spent the last three seasons with the Cleveland Browns.