I don't even know *what* that was about.

Every time I see a reference to that line from Emancipation where Jack is reminding Carter about "that time on P3X-595" where she "drank that stuff that made you take off…", I mentally fill in "YOUR HEAD." Because it's so obvious what the joke is going for, and I just really have to subvert it in some way.

So yeah. In my braincanon, early in their first year, some weird reality-warping (and/or mutual hallucination) crap went down on P3X-595 which resulted in Carter taking off her head and possibly walking around with it under her arm for a while. And it was creeptastic enough that once reality reasserted itself, she decided never to mention it again.