Col Carter vs Lt Col Carter?

[Cad.biker]

What’s up with Col. Carter getting demoted when Wolsey replaces her on Atlantis ?
In Atlantis she was a FullBird Col.
She mentions at the end of season 4 going to the extraction ceremony of Ba’al which is Continuum I which she is a Lt. Col. What gives ?

[NickEast]

It's an error in the credits, same for Mitchell. They both were promoted to full-bird Colonels by the end of SG-1 and neither were demoted.

[Cad.biker]

It not the credits. It is actual dialog and rank.

[DigiFluid]

Ark of Truth (where both characters are Lt Cols) started production in early 2007, shortly after they wrapped filming the regular TV series, and they went straight into production of Continuum after AoT. Several of the shots used in Continuum were actually filmed as part of the Ark of Truth shoot, because there was some thought given to having the first movie set up the second (though obviously this idea was eventually dropped).

Atlantis Season 4 was also filming in this same period, the time at which Amanda Tapping joined the show and her character got an in-universe promotion.

It was during filming of the movies, and when they figured out that Continuum wasn't going to be released until after Atlantis Season 4 finished airing, that they realized the rank change and had to make modifications on the fly -- in Continuum, you can see during the F-15 scene that both her and Cam are wearing full colonel insignia, despite costuming elsewhere in the movie and the end credits listing them as Lt Col.

There were no demotions, it's just a real-world production/costuming mistake; the sort of thing that's not unexpected when you're juggling the same actress across concurrent production of two films and a TV season, all of which are set within the same universe.