Board Thread:Show-Related Questions and Answers/@comment-5344051-20160229080952/@comment-25536775-20170501195615

Killian Jones wrote: Not really. It is a lot more reasonable to say they were within the reach of the Dark Curse when the curse was cast. I'm pretty sure Adam was asked about this on twitter and answered something along the lines of "we don't know where Jefferson was when the curse was cast." Occam's Razor. It's simpler to believe that Regina was telling the truth and had the ability to take individuals from other realms if she wished to than believing somehow both Whale and Jefferson happened to be able to travel through realms using unknown means and were  at the Enchanted Forest at the exact moment of the casting of the Dark Curse.

There's nothing too unbelievable about Regina being able to bring individuals from other realms, given that the DC is extremely powerful.