The sound effect used in the film when the sonar pulses are sent out is the same one that was previously used in the film The War of the Worlds (1953) when the alien "periscope" is scanning the area after it has been constructed by the occupants of the cylinders.
At 26:02 into the film, when Dr. Michelle Herman (another nod to author Herman Melville) wants to listen to a cassette tape, she presses RECORD. She should have pressed PLAYBACK.
At 8:35 into the film, a newspaper headline refers to "secuirty forces". The correct spelling is "security".
Error in the rolling end credits in the line: "Art Production Assistants JEAN KIMBERL". As only one person is listed it should be "Assistant"
In the first five minutes of the film, an American submariner refers to a new Soviet submarine as "Yankee Class". It is very unlikely that the Soviet Navy in 1969, or at any time, for that matter, would designate any of its vessels as "Yankee" .