it does seem like a slight continuity error. At first I though she managed to escape by just slipping her hands out of the restraints but the image before this one shows that she had undone the chain/rope/strap that was holding her at the end of the bed so why would she do that if she could just slip her wrists out. Although lurker could very well be right, as the mistress does seem a little more submissive than her character has been established as. And this incident did occur right after slave girl crawled to the end of the bed to go to sleep.
You can't slip anything by us Admin, you have a high class audience here, we demand the highest of standards!
BTW do you have a general idea of the overall plot arc for the comic or do you just kind of make it up as you go along?