- “Hooray for Duncan's mistake!”
- ―The narrow gauge engines
The Runaway Elephant is the sixteenth episode of the seventh season.
A new park is being opened and Duncan is bossing the other engines about and telling them to do their work quicker. When Duncan finishes his jobs, he is asked to take an elephant statue down to the park, but carelessly leaves without a brake van. Duncan also ignores the warnings to slow down and thus runs out of control, finally derailing at the park and sending the elephant flying into the pond. Duncan is repaired in time for the opening, but is surprised to find the elephant still in the pond due to general favour of the elephant's position, and embarrassed to be lauded by the others for his fortunate mistake.
- Sir Topham Hatt
- Lady Hatt
- The Tea Room Station Stationmaster
- Rheneas (cameo)
- Peter Sam (cameo)
- Headmaster Hastings (cameo)
- Cyril the Fogman (deleted scene cameo)
- Skarloey Railway Depot
- Whispering Waterfall
- Elephant Park
- Rumblin Bridge
- Tea Room Station
- Trestle Bridge
- Rocky Ridge Line
- Going by production order, this is the twenty-third episode of the seventh season.
- A deleted scene from The Old Bridge is used.
- This is the fourth episode to date to use a rendition of Gioachino Rossini's "William Tell Overture (Finale)" and the second time it's used in the seventh season. The first being Busy Going Backwards, the second being Thomas the Jet Engine, and the third being Rheneas and the Roller Coaster. However, like the aforementioned episode, this was only in the UK and international versions, and unlike the previous episodes, the music was only played briefly.
- The events of this episode were later mentioned by Duncan in the eighteenth season episode, Emily Saves the World.
- When Duncan arrives at the sidings to collect the statue, the trucks that were previously there when he was at the station have disappeared. Also, Duncan arrived from a dead end.
- In one scene, Duncan's driver changes appearance.
- When Duncan rushes past Rusty, the narrator says: '"Slow down!" whistled Rusty,' but Rusty is a diesel engine and diesels have horns. Also, the line behind Rusty leads to bushes.
- When the narrator says that people waved and cars tooted, Elizabeth and Sir Topham Hatt's Car's horn sounds are heard, but they are nowhere to be seen.