Gordon travels in Thunderbird 4 to recover Braman but discovers that the Chaos Crew have gotten to the robot first. An underwater battle ensues and both Thunderbird 4 and Gordon are harmed.
- Scott Tracy, Alan Tracy - Rasmus Hardiker
- Virgil Tracy, Gordon Tracy - David Menkin
- John Tracy - Thomas Brodie-Sangster
- Kayo - Angel Coulby
- Kayvan Novak - Brains
- Grandma Tracy - Sandra Dickinson
- Lady Penelope Creighton-Ward - Rosamund Pike
- Parker - David Graham
- Havoc - Aimee-Ffion Edwards
- Fuse - Craig Stein
- The Hood - Andres Williams
- Captain Wayne Rigby - Marc Silk
- Braman - David Graham
International Rescue Equipment UsedEdit
- Thunderbird 1 (cameo)
- Thunderbird 2 (Module 2)
- Thunderbird 3 (cameo)
- Thunderbird 4
- Thunderbird 5 (unseen)
- Thunderbird Shadow
- FAB 1
Non International Rescue Equipment UsedEdit
- From a show that tries its best to shy away from violence, SOS Part 2 took a sharp turn away from that trend in several areas:
- The Hood successfully brings about the injury of a main character (Gordon), harking back to the earlier mythos surrounding the character.
- The attack leaves Gordon unconscious for an extended amount of time, the first time a character has done so.
- Gordon is left hospitalised, and his injuries are indicated to take many months to heal. The extent of these injuries, however, is left unclear - Gordon jokes that his sense of humour is the only thing not broken.
- During Thunderbird 4's Launch sequence a model of Stingray is in the aquarium
- Thunderbird 4 is destroyed for a second time. However, unlike Up from the Depths Part 1, the wreck is left at the bottom of the ocean and its future, much like its pilot, is left unanswered.
- After Thunderbird 4 is taken out of action, Thunderbird 2 is shown to have pod configurations that are capable of being submerged below water. Notably, these pods are yellow in colour, as opposed to the green they had briefly become earlier on.
- It could be believed that these pods could belong to Thunderbird 4.
- This is also the first time that any module other than Module 4 has been deployed onto the water.
- Thunderbird 4 is shown to be able to operate in reverse. This is the first time such maneuvers have been seen.
- This is the first underwater rescue performed by Scott.
- The cliffhanger ending of this episode is expected to lead directly into Signals Part 1, with Brains discovering that Jeff Tracy may still be alive. Apart from the vague link between Touch And Go, Undercover and Legacy back in season 1, this is the first time a storyline has pushed beyond two episodes.
- It is quite a dark notion that Jeff is alive and "all alone" (according to Braman) over nine billion miles away. Such darkness was established for the first time in this series (see above).
- According to the credits, a GDF pilot is voiced by Angel Coulby, however, the actress only voiced Kayo in this episode.
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