... the Star Trek tv/film continuity is massively broken [snip] according to "That Which Survives"
Massively broken is a bit overstating it, a little bent and crooked in places, is all.
Some alien technology in That Which Survives was used to move the Enterprise 990 some light years, the Enterprise, probably unknowingly, simply returned back through it. A corridor that persisted for a time, maybe how the Kalandans moved their own ships. Akin loosely to the soliton wave perhaps (imho).
No worst a concept than simply going with continuity is all screwed up.