The Friendly Physician - S2-E29
Factual error: When the castaways are coming back to the island at the end, you can see some of the Los Angeles buildings in the background in the high camera angle.
Factual error: An edition of the 'Melbourne Herald' newspaper can be seen in this episode, and appears to be dated Friday, December 24, 1964. Yet 'Thunderbirds' is supposed to be set in the 21st Century (2026 or 2065, depending on who you believe). This date is also seen on newspapers which appear in the episodes 'Edge of Impact', 'The Impostors' and 'Cry Wolf'. Also, to compound the error, December 24th, 1964 was actually a Thursday, not a Friday.
A Vision of Sugar Plums - S1-E15
Factual error: Samantha looks out a back dormer window to see Darrin in the front yard.
Factual error: On the map of Scotland that Troy and Phones are looking at, Glasgow is spelt "Glascow."