Runaway Engine

Runaway Engine is the fifth episode of the twenty-first season.

Plot
Millie is given extra work around the estate and gets agitated when Stephen and Glynn forget to clear up the garden waste. When Stephen also manages to hurt her feelings, and can't find her the next day to apologise, he thinks that she must have run away.

Characters

 * Stephen
 * Glynn
 * Skarloey
 * Luke
 * Millie
 * Sir Robert Norramby
 * The Grumpy Passenger
 * Rheneas (cameo)
 * Sir Handel (cameo)
 * Peter Sam (cameo)
 * Rusty (cameo)
 * Owen (cameo)
 * Mr. Bubbles (cameo)
 * The Welsh Bird Watcher (cameo)

Locations

 * Ulfstead Castle
 * Blue Mountain Quarry
 * The Dinosaur Park
 * Crovan's Gate (mentioned)

UK/US

 * Bob Golding as Stephen
 * Keith Wickham as Glynn, Skarloey and the Grumpy Passenger
 * Michael Legge as Luke
 * Miranda Raison as Millie
 * Mike Grady as Sir Robert Norramby
 * Teresa Gallagher as Some Passengers

Trivia

 * A few references to the seventeenth season episode, The Switch, are made.
 * This is the fourth episode, to have the exact same voice cast in both UK and US dubs after the seventeenth season episodes, Luke's New Friend, The Switch and the twentieth season episode, Blown Away.
 * This is the first episode since the eighteenth season episode, Samson Sent for Scrap in which Thomas does not appear in any way, or even any member of the Steam Team in that matter.
 * Going by production order, this is the sixth episode of the twenty-first season.

Goofs

 * When the Grumpy Passenger trips over Stephen's buffer bream, Stephen's whole frame is shifted over.
 * When Stephen and Glynn discovers the garden waste, Stephen's shed doors is shut. But when Millie puffs on the turntable, the doors are open. Also, since the waste is right in front of the door, there is no way the doors can open that wide.