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.
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.
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.