One thing that helps me deal with continuity problems on DS is my own personal view of time travel that I finally happened upon not too long ago. In this view, whenever a person travels from Time X (let's call it Time X1) to another Time Y, they actually begin a new parallel time thread branching off from the "original" Time Y (let's call it Time Y1), which could be called Time Y2. Then, when they return to Time X, they are not in Time X1, but in a new parallel time thread Time X2. So whenever a character is in a non-native time, that is a parallel time, not the "original" version of that time. And when they return to their native time, it's probably a parallel time, not the original version, because it has effects that could only have occurred in a parallel thread. So once Vicki went back to 1795, we never ever got back to the original time thread that the series started out in; we got to a thread that had branched off from her point of entry in 1795. (In the original time thread, she never exists at Collinwood until 1966.) The DS storyline then just follows the time thread that the time traveller is travelling along.
And if there are any continuity problems that occur within a specific story arc where nobody has done any time travel between the original mention of a certain detail and the revised version of that detail, maybe we can just assume that one character or another has done some sort of time travel that happened offscreen.