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)
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)
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)
Deliberate mistake: The huge system and missile control boards containing the failsafe units suddenly appear on Seaview's bulkheads just for this episode. And of course, they disappear after this, never to be seen again. (00:15:00)
Deliberate mistake: "The X-Factor": When the helicopter is chasing Nelson's car, re-used footage from a first season show briefly turns the otherwise color episode black and white. (00:24:00)
The Return of the Phantom - S2-E26
Deliberate mistake: Kroeger's ghost takes over Crane's body when the captain is injured, but still alive. In "The Phantom Strikes," Kroeger told Nelson his host had to be dead first. This "fact" needed to be altered in the sequel so that Crane could survive to be rescued at the end. (00:16:00)
