At the Outlander San Diego Comic-Con panel this year, Graham McTavish (Dougal) made a surprise appearance in the middle of the panel. Graham is no longer on Outlander, but he is on Preacher which had its own panel going on in Hall H around the same time as the Outlander panel in Ballroom 20. Access Hollywood spoke with Graham, Sophie Skelton, and Richard Rankin about the surprise (and it was that to everyone on the panel). Sophie and Richard continue to speak about Outlander season three, and methinks Richard had a drink or two before hitting the red carpet.
Source: Access Hollywood on YouTube