An engine shortage has arisen and the only engine available is a Diesel, who insults the engines almost immediately after arriving. The engines are furious, but cannot think of a plan for revenge. There is no need though, as the Diesel sucks an inspector's bowler hat through an air-intake vent just after starting. Duck and Stepney take his train, and reach Crovan's Gate in record time. Stepney leaves the next day and, while the engines bid him farewell, the Diesel creeps sulkily away, leaving only two things to remember him by, a bad smell and a battered bowler hat.
- Donald and Douglas
- The Diesel
- Sir Topham Hatt
- Edward (does not speak)
- Thomas (cameo)
- Percy (cameo)
- Skarloey (cameo)
- Sir Handel (cameo)
- Rusty (cameo)
- Bertie (cameo)
- Annie and Clarabel (cameo)
- Stephen Hatt (cameo)
- Tidmouth Sheds
- Gordon's Hill
- Crovan's Gate
- Skarloey Railway Engine Sheds
- Shunting Yards
- Henry's Tunnel (deleted scene)
- This episode is based on the story of the same name from The Railway Series book, Stepney the "Bluebell" Engine.
- This marks the final appearance of Sir Handel until the tenth season.
- In a rare picture, Gordon is in Henry's place when the Fat Controller makes the announcement.
- The Norwegian title of this episode is "The Bowler Hat". In Italy it is "The Diesel Railcar". The German title is "Hitting Out". The Japanese title is "Prevention and Diesel". In Wales, this episode is called, "Tribulations of the Hat". The Danish title is "Bowler Hat". The Spanish title is "Diesel Will Have To Learn".
- According to the description on Thomas and the Special Letter and other stories, the Diesel was brought to Sodor to take over Daisy's work while she was ill.
- This marks the first time Donald and Douglas appear and speak in the same episode since season 2.
- The goods train next to James is being pushed by a crew member, as a shadow is seen.
- When the Diesel arrives, James swaps tracks from the left of Donald and Douglas to the right and then back again.
- A pipe can be seen on the Diesel's air-intake in the close-up of the inspector's hat.
- Stepney is missing his crew in the first shot.
- When the Diesel breaks down, he has his air-intake covered, but when the inspector notices his hat, his air-intake cover is off.
- In the Spanish version the Diesel is called Diesel in the title card.
- In the close-ups of Duck and Stepney during the scene where the Diesel breaks down, the scenery changes.
- In the shot of Duck and Stepney puffing up Gordon's Hill, a red and blue wire can be seen in the middle coach. In the same shot, the track in front of the engines appears to sink just before they roll over it.
- Stepney says "James says he's as sick as boiler sludge and sulking in the shed!" but Gordon should have said that, since Duck and Stepney arrived after James left.
- James has Smudger's whistle sound when he leaves the station.
- Gordon has Duck's whistle sound when he leaves Crovan's Gate.
- Stepney has Rheneas' whistle sound.
- After The Diesel grinds to a halt and the camera switches to Duck and Stepney and then back to The Diesel, he is slightly farther away from the coaches.
- When Duck and Stepney reach Gordon's Hill, Duck gains a lamp.
- Gordon is missing his brake pipe.