Look closely at Harold and you'll see his mouth is actually in the sad expression, quickly repainted to look happy.
In one of the scenes at the very beginning of this episode, Clarabel is, again, facing the wrong way.
Percy: I want to be useful where I can't get dirty!
Driver: There's a load of sugar going to the chocolate factory. We can take the sugar trucks.
Percy: Sugar? That's nice and clean.
Percy: I get dirty. I need washdowns! Gordon only does it to feel important.
Gordon: I am important. I'm an express engine.
James: You're a pouty puffer, Percy.
Percy: No, I'm not!
Don't look back.
Dirty Percy's on our track!
Thomas: You look good enough to eat!
James: Pudding Percy!
Henry: Choc ice on wheels.
The Fat Controller: Usefulness before cleanliness.
Appearances by Percy, Thomas, Henry, Gordon, James, the Troublesome Trucks, Harold and the Fat Controller.
This episode makes use of two 'breakaway' walls, specially constructed props that are built to easily break-away upon impact/pressure. These are used on both ends of the Chocolate Factory.
We learn that Percy often gets the dirtiest jobs.
First appearance of Mr. Jolly's Chocolate Factory.
First (and only) appearance of the Mr. Jolly's Chocolate Factory Trucks.
This story is similar to one called 'Choco Boco' which featured in an old Thomas magazine.
Mr. Jolly's Chocolate Factory
The name of the factory sounds similar to "Willy Wonka and the Chocolate Factory", the title of a 1971 movie.