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.
Continuity mistake: In the Thompson Tower at one point, Blanche and Tommy are sitting on a bench whilst Joe keeps hitting the steel door. When the Tower Control assistant switches on the television, he says "How did they get in there?" and we see a picture of the family. This time, it's a different picture to the one seen before as Blanche and Tommy are not sitting on a bench, and Joe is nowhere near a steel door.
Continuity mistake: When we see Virgil in his sick bed after crash landing on Tracy Island, he has a bandage around his head and there is a blood stain on the bandage above his left eye. But when Gordon comes into his room to watch the moving of the Empire State Building on television, the blood stain has disappeared.