Continuity mistake: During the second rescue, Thunderbird 2 releases the pod containing Thunderbird 4 on the water. But when we see Thunderbird 2 next to the collapsing oil rig, the craft can be seen with the pod in it.
Other mistake: When Lady Penelope is counting her sheep, Parker had just told Jeff that she has 200,007 sheep. When we see her using the sheep-counter machine its display only has five digits instead of the necessary six. (00:14:35)
Visible crew/equipment: When Hooper says "Sound the alarms!", you can see a hand moving Hooper's legs as he gets up from where he is sleeping.
Continuity mistake: When Thunderbird 4 comes out of the pod with the sealing device, there is a "4" on the back of the craft, but when it goes to clamp the device over the base of the fire jet, the "4" has disappeared.
Audio problem: When the Atom Sub Reefer Captain says "OK, Lieutenant, dive." it is said by Jeremy Wilkin instead of Ray Barrett.
Continuity mistake: When Sir Harry drives Lady Penelope down to FAB1 in his jeep, he is wearing a yellow helmet in the zoomed-out shot. When he is seen in close-up he is no longer wearing the helmet. Then, when the shot zooms out again, he is wearing the helmet.