Back and Back and Back to the Future - S1-E3
Visible crew/equipment: After Matala's shuttle and the Scorvian cruiser are torn apart by the black hole, when it cuts to Rygel in the galley as he burps just before John walks in, we can see the puppeteer's right arm and hand (wearing a wedding ring) behind Rygel.
Chosen answer: It's never explained. John mentions a theory that his less technologically developed craft simply interferes with the wormhole less than the "superior" Vipers, but they never make a concrete determination on that point. But we also have to take into account the fact that Moya traverses wormholes with no ill effect as well.
Garlonuss ★