Despite the fact Oink is seen in this episode he does not speak, meaning David Graham does not take part in this episode but is credited.
This is the only time the Marineville Tracking Station is voiced by Lois Maxwell instead of David Graham.
Commander Shore's dialogue at the end of the episode (considering improving Marineville's early warning system and preparing Stingray to go even deeper) implies that this episode takes place before Emergency Marineville (1964), Subterranean Sea (1964), Marineville Traitor (1965), The Master Plan (1965), Invisible Enemy (1965), Deep Heat (1965) and A Nut for Marineville (1965).
This episode was the 6th episode produced and the 17th broadcast.