Tillie to the Rescue is the first episode of the original first season and the pilot special of The Railways of Crotoonia. It first aired in workprint form on August 19th, 2017 and made its proper premiere on August 21st, 2017.
The special was first developed in 2014 as a regular episode of the series, but as the series switched to a ten-minute episode format, the episode became a half-hour special that would take three years to complete.