Other mistake: At the end of the episode in the space rocket Scott says "you can say that again" without moving his lips.
Thunderbirds (1964)
1 other mistake in The Impostors - chronological order
Starring: David Graham, Ray Barrett, Peter Dyneley, Shane Rimmer
Revealing mistake: When the dummy plane is shot out of the sky by the fighter pilot, a piece of the plane shoots off into the top left of the screen and bounces off the sky background. (00:23:05)
Trivia: Jeff Tracy's five sons were named after Mercury astronauts - Scott Carpenter, Virgil Grissom, Alan Shephard, Gordon Cooper and John Glenn.