This is the only time during a rescue mission where Thunderbird 1 is used as a piece of rescue equipment rather than just an observation and control ship.
Mentioned in Security Hazard.
The dynamic seen in TB1, where the pilot must adjust from a vertical to a horizontal flight path, would be employed in the real life space shuttle flights, which launch vertically but return horizontally.
When Tin Tin's character is first introduced, Mr. Tracy mentions she has completed her university studies in the U. S. and then gone on a grand European Tour. So it's likely she had some romantic encounters. Both this episode and The Cham Cham explore that aspect, to Alan's extreme consternation. The relationship he pursues with Tin Tin is only hinted at, however.
In the future when the show is set, the Tracy family still peruses the very latest newspapers and magazines, though no mention is really made of a regular postal service. Tracy Island is close enough to allow for supply shopping trips, however. So the mail gets through somehow.