This is the only episode to feature the entire regular cast (the five Tracy brothers, Jeff, Lady Penelope, Parker, Tin-Tin, Brains, Kyrano, Grandma and The Hood).
This is the only episode where Lady Penelope is seen on-board a Thunderbird machine (in this case Thunderbird 2).
This is the only time in the original series Parker is seen on Tracy Island. (He would be seen on the island again in the Kickstarter-funded episode Introducing Thunderbirds (2015).)
This is the only episode where Thunderbird 2 lands on the ground without the pod in place.
In the episode "The Mighty Atom", the teletype printout gives the date on which the atomic cloud is blown away from Melbourne as 6 October and it is then stated that the explosion at the plant took place the previous Monday. If this is 2064, the explosion therefore occurred on 29 September. It is also stated in this episode that International Rescue were not operating when the Australian plant exploded in 2064.