The metal that the giants are homing in on, "inella," is an anagram of series creator Irwin Allen's name: I Allen.
This was the first of two appearances on the show by Irwin Allen's wife Sheila Allen. However, she was still using her maiden name of Matthews.
This is the first time that Dan's being a former Olympian is mentioned.
Per the title, a lodestone is a naturally occurring magnet that is usually a magnetized piece of the mineral magnetite. They can attract iron and have been cherished since ancient times for their magnetic or seemingly magical properties.
This was the first time the public saw Kevin Hagen as the castaways' nemesis Inspector Kobick, but it was actually the second episode produced with Kobick as it was 19th in production order. The 18th episode in production order "Genius at Work" was originally intended to be Kobick's first appearance, but it was broadcast as his fourth, after his second appearance in the 21st in production order "Seven Little Indians" and third appearance in "Target: Earth."