Continuity mistake: When Scott and Virgil are performing the rescue operation, watch the position of Blanche Carter. When we see her she is sitting down unconscious near the bench where Tommy is lying, but just a few shots later she is standing up next to Joe, and then later she is sitting down unconscious again.
Continuity mistake: Before going on board Thunderbird 3, Alan is wearing a brown suit and Scott is wearing a yellow suit and orange shirt. But when Alan goes up the elevator in Thunderbird 3, his clothes have changed to a green checked shirt and beige trousers, and when Scott returns to Tracy Island, his clothes have changed to a blue roll-neck and checked jacket.
Continuity mistake: When Thunderbird 1 arrives at the danger zone, there are no markings down the length of the vehicle when it lands, but lettering appears after Scott calls for help with his equipment. This lettering is in a completely different font to that seen on the vehicle during the launch sequence.