Thomas and friends work together to restore an old castle and find a missing friend, Stephen - the Real Life locomotive Stephenson's Rocket with an added face.
King of the Railway contains examples of:
- Animation Bump: The animation as of this special is much more fluid, due to the show being animated by Arc. As a result, the sky is bluer, the trains' smoke is more detailed, and better camera angles are used. The trains' facial expressions are also more exaggerated, making a wider range of emotions.
- Art Shift: The introduction to the now ruined Ulfstead Castle has medieval-themed illustrations to tell the events that happened to it.
- The Big Race: Caitlin and Connor have one along with Gordon and Spencer at the end of the movie.
- Brick Joke: The suit of armor that Percy spots throughout the movie. Near the end, Norramby wears it.
- Cannot Keep a Secret: Thomas can't resist telling a downbeat Stephen about his special job, pivoting the chain of events.
- Creative Closing Credits: The credits play over a montage of scenes from the movie.
- Earn Your Happy Ending
- Freudian Trio: Thomas, James, and Percy end up forming one in this movie.
- Musical Chores: "Working Together Again".
- One Steve Limit: Stephen shares the name of Sir Topham Hatt's grandson.
- Take That!: The issue of Henry's coal. For context, during the Sharon Miller era, it was said Henry still needed special coal, even though his new shape was meant to remedy this. Oftentimes, this special coal need was nothing more than convenient plot device, and in some cases, the writing made it sound like a G-Rated Drug, when it really wasn't. The following line was put in by Brenner to put the issue to bed once and for all:Toby: Henry's broken down!
Gordon: Don't tell me he needs Special Coal again...
Toby: No, Gordon, that was fixed YEARS ago!
- Wham Episode: Ulfstead Castle is restored, and Stephen found King Godred's crown.