Continuity mistake: The broken section of monorail track that is attached to the top of the centre coach when Thunderbird 2 lifts it away from the bridge is significantly longer when Virgil sets the coach down on the mountainside.
Other mistake: Just as the villains' car goes out of control in the opening sequence, a huge lump of greenery falls out of the sky in the background.
Deliberate mistake: When Selsden and Malloy try to open Penelope's safe, the bulb in Malloy's torch gets so hot that the prop torch begins to smoulder.