When West mentions the name of the recently married friend who gave West his little black book, the name of the friend is Irving Moore. Irving J. Moore directed 26 episodes of The Wild Wild West (1965), and before that had directed 14 episodes of the earlier Robert Conrad series Hawaiian Eye (1959).
The Dodge City exterior set from Gunsmoke (1955) is unrecognizable in its redress as the San Francisco waterfront in the opening act. At least not until West enters the familiar Longbranch saloon interior. In one of the more creative uses of the Dodge City sets, a seedy waterfront bar is created using what appears to be the Dodge livery stable.
When we first see Dan, the prophet of doom, he begs a coin from West by saying "Even a Cassandra must live". Greek mythology, Trojan War, Crassandra was a princess of Troy. She was cursed to accurately see and proclaim the future, but no one ever believed her.
This is the second time in the series where Jim West has to get into a gigantic underwater facility, after The Night of the Watery Death (1966).
Jason Evers and Marj Dusay have both appeared in the series Ironside(1967)