Continuity mistake: The video set turns on before Admiral Nelson activates the "on" switch.
Continuity mistake: When the four divers exit the Seaview, each has a flashlight. When the reach their destination only three have flashlights.
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)
