Thomas, Edward, Henry, Gordon, James, Percy, Toby, Annie, Clarabel, Henrietta, Bertie, and The Fat Controller (known in the American dubs as "Sir Topham Hatt") are the only characters who have appeared in every season of the series.
Three real engines have been featured on the show - Stepney has made a number of appearances, and City of Truro and Flying Scotsman played minor roles in the third season. The Flying Scotsman also appeared in "The Great Race" and in "Journey Beyond Sodor".
The episode "the Missing Coach" is a known episode to be cancelled. The reason it was cancelled was because Britt Allcroft thought the plot was to confusing for children to comprehend. "Gordon Goes Foreign" was also a cancelled episode because the budget was too high.
In 1953, a previous attempt was made to adapt "The Sad Story of Henry" for television, but this was unsuccessful. This was because the model of Henry derailed and a human hand had to place it back on the rails. This attempt was much more successful because of the way that the miniature engines were set up and filmed.