Continuity mistake: Interior shots of the flying sub sows the sub rocking violently but exterior shots show the sub lying still on the sea floor.
Continuity mistake: The shot from the rear of Kowalski and Nelson shows Kowalski holding the scanner. The next scene Nelson asks Kowalski what is on the scanner and then tells Kowalski to pick it up.
Continuity mistake: During the battle a railing on a pirate ship falls off, only to be seen in the next shot intact, then missing in a subsequent shot.
Character mistake: Captain Crane has Bentley collared and is questioning him. An alive Lee Crane asks Bentley "why did you kill me?" He quickly changes it to "why did you try to kill me?" (00:10:40)
Revealing mistake: While the Seaview rocks violently back and forth from the concussion of the under water explosion, the pencils, folders, papers, etc., on the navigation table do not move.
Visible crew/equipment: The shadow of the camera is visible as Captain Brent walks the Seaview's corridor.
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)
Factual error: Crane clears an Air Force jet to land at the Antarctic ice station. But the station is located on a completely snow-covered sheet of ice with no runways. How and where could it possibly land? (00:27:30)
Continuity mistake: Nelson spins the roulette wheel. We see a close-up of the wheel slowing down. Cut back to a full shot, and now the wheel is spinning faster than ever, even though no one has touched it. (00:42:15)
The City Beneath the Sea - S1-E2
Revealing mistake: When Seaview's crew recover the diver's body in the beginning and clear seaweed from his mask, the "dead" man is blinking. (00:01:20)
Factual error: The Seaview's military history computers need an upgrade. The derelict German sub is identified as a WWI ship, the U444, supposedly sunk in 1918. There were only 167 U-boats in WWI. U444 wasn't built until 1942. And the sub's design is definitely WWII, not WWI. (00:02:30)
Deliberate mistake: The Seaview's 8 huge picture windows were a concession to design over practicality. Though they knew that such big windows could never withstand deep sea pressures, the producers wanted the characters - and the audience - to be able to see all the underwater wonders "up close." The "impossible" windows became one of the show's most popular features. (00:25:10)
Revealing mistake: Crane overcomes his guard in a fistfight by hitting him in the face three times. But if you watch closely, it's apparent that not one of his blows connects. He "strikes" the air above the man's head all three times. (00:32:00)
Deliberate mistake: "The X-Factor": Car-wreck stock footage turns the admiral's 1965 sedan into a much shorter, fatter 1950s model when it bursts into flames and rolls down the embankment. (00:26:00)
Factual error: The diving bell descends to 4000 feet, where no light can penetrate and the ocean around them should be pitch black. But some strange, unseen phenomenon is lighting up the bell quite nicely for the camera. (00:21:15)
Plot hole: The Seaview's crew have a wild shootout aboard ship, and their bullets are seen to go all the way through a 6-inch-thick hatch door. Gee, you'd think that somewhere during their military training, somebody would have taught these guys why firing high velocity weapons on a submerged submarine is a really bad idea. (00:38:15)
Factual error: The derelict sub is said to have suddenly moved itself more than 30,000 sea miles from its original position. This makes no sense. The entire circumference of the Earth is only 22,000 sea miles. And if the sub had somehow circled the globe plus an additional 8,000 sea miles, there'd be no way to tell that it hadn't simply moved just 8,000 miles. (00:08:10)
Continuity mistake: Nelson takes the captured assassin's knife and says that Alicia was killed with one just like it. But he can't possibly know that. He never saw the body or the weapon. Only Crane was with Alicia when she was murdered, and Crane, still missing in action, hasn't been in contact with Nelson. (00:42:15)
The Cyborg - S2-E4
Continuity mistake: At the end, Crane shoots The Cyborg Nelson in the forehead. It clutches at its completely intact face and falls down. We cut to crew reactions and then back to the fallen cyborg - and now its head is nothing but a jumble of circuits. Were those delayed-action bullets in Crane's gun? (00:46:40)
Deliberate mistake: Several of the roaming dinosaur segments here are repeated 2-3 times over. They're all recycled footage from producer Irwin Allen's own 1960 remake of "The Lost World," and Allen must have wanted to get as much use out of the dino shots as possible. (00:28:00)