All of the submarine sets (including the conning tower) were re-used from Ice Station Zebra (1968).
Second unit footage of the submarine cruising on the surface, submerging, and surfacing were from Ice Station Zebra (1968). Some of the underwater special effects shots were also from Ice Station Zebra (1968).
Ron Masak, Lee Stanley, and Lloyd Haynes appeared in Ice Station Zebra (1968).
Leonard Nimoy and Lloyd Haynes and William Windom appeared on Star Trek (1966). Also appearing in Star Trek (1966) was Malachi Throne and John Winston.
Leonard Nimoy is credited in Mission: Impossible (1966) along with Sam Elliott, Malachi Throne, Ron Masak, and Ron Masak.