The City Beneath the Sea - S1-E2
Continuity mistake: Seaview is on the ocean floor investigating the underwater city. Two inserted stock shots then show it up near the surface at periscope depth. In the next shot, though, it's back on the bottom again. (00:43:15)
The City Beneath the Sea - S1-E2
Continuity mistake: Seaview's windows form 8 horizontal rectangles in 2 rows across its bow. But the interior sets have windows that form vertical rectangles, and they're much closer together than they are in the exterior shots. (00:02:30)
