In his autobiography, Sir Roger Moore wrote that at one point, the crew tried to sedate several of the lively cats that belonged to his character, without actor and cat lover James Mason discovering the scheme.
Approximately one thousand seasickness tablets were issued to cast and crew members working on-board scenes filmed on the ship the "Tor Viking". Pills would be handed out every four hours, and if they didn't work, an injection in the butt from the nurse was the alternative remedy.
The "Scottish" castle seen in the movie was not in Scotland. It was Dunguaire Castle, which is near the village of Kinvara, County Galway, Ireland.
David Hedison wrote on February 26, 1979: "At this writing, there is a possibility I might be working on a motion picture called 'Esther, Ruth, and Jennifer', a story about a gang who attempt to hijack three destroyers in the English Channel. I'm not one of the gang, I'm a good guy!!! It will be filmed in London and the Channel Islands in late April and May. If this particular deal works out, it will be nice to return to Europe again."