 "Model Spy" is the first episode in the series' production order to reveal their full real names as Paul Metcalfe and Adam Svenson.The miniature monotrain was designed by special effects assistant Mike Trim.As the suspended monotrain built for the "Thunderbirds" episode "Brink of Disaster" had been difficult to shoot effectively, Trim designed the new train to run on a OO gauge model railway track, which proved much easier to film.