The red scaffolding structure supporting the Enpire State Building is the same as that at the rear of Thunderbird 2 while it undergoes repairs.
Thunderbird 1, Thunderbird 2 with pod 6, Thunderbird 4, Firefly, USN Sentinel, Atomic Building Engine
The back of cameraman Joe's head flies off as he falls into the cavern.
As Ned and the cameraman swim into Thunderbird 4, you can see the edge of the model used to represent Thunderbird 4's cockpit roof. Look to the far right and you can see that the side pod things start, then stop when they should go all the way back.
Thunderbird 4's engine makes a very deep buzzing sound, rather than the normal high-picthed hum, in this episode.
When Thunderbird Four is buffeted to the ground at the end of the story, drops of water can be seen running down the outside of the tank.
As mentioned in the notes, Godber can be seen at the Ned Cook Show at the front of the audience, but when the camera pans along the Tracy family, who are seated at the back of the audience, Godber has relocated himself to just in front of Jeff.
Ned Cook: In a few moments, the National Television Broadcasting System will show you a construction job that leaves the building of the pyramids in the shade. Today, the Empire State Building here in New York City is going to be moved 200 yards, not piece by piece, but as it stands – all 1,250 feet of it.
First appearance of Thunderbird 4.
This is the first and only time Thunderbird 4 is seen launching along Thunderbird 2's runway.
Contrary to the theatrics of the special effects department, bulk-erasing video tape will not cause it to smoke.
Among the audience at the Ned Cook show at the end of the episode are Doctor Godber (The Perils of Penelope) and producer and agent Bletcher/Maxie (Martian Invasion/The Cham-Cham).
In the 1980's, this episode and Atlantic Inferno were paired together for the ninety-minute American compilation film Countdown to Disaster.
John, Lady Penelope and Parker don't appear in this episode. Grandma appears at the end of the episode but does not speak.
Although credited on the end titles, Sylvia Anderson does not take part in this episode.
Although filmed as a 25-minute episode, it had to be brought up to 50 minutes afterwards. Some of the added footage included the oilrig fire at the beginning of the episode.