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.
In the first 11 seasons, the show used live-action models exclusively. Season 12 used a mix of CGI and models. However, as of Season 13, it's entirely animated in CGI.
PBS aired a spin-off called Shining Time Station (1989) from 1989-1993. This was created to introduce Thomas the Tank Engine to American viewers.
In 1953, a previous attempt was made by the BBC 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.
In the first two seasons, it was narrated by Sir Ringo Starr, the former drummer of The Beatles.
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 too confusing for children to comprehend. "Gordon Goes Foreign" was also a cancelled episode because the budget was too high.
In season thirteen, it was revealed that Sir Topham Hatt's first name is "Bertram", and he is also shown to have a brother named "Sir Lowham Hatt".
Even though he doesn't appear in every episode, Gordon has the most amount of cameos out of any engine since he pulls the express train.
Britt Allcroft, the creator of the series picked Sir Ringo Starr as the narrator when hearing his voice on television. She then thought it would relate to children.
As the narrator of the American version, George Carlin was nervous about recording his narration without an audience, so the producers put a stuffed teddy bear in the booth with him.
Toby and Oliver are the only two main cast steam engines that do not converse with each other during the entire series to date. However, they do briefly share screen time in the Season 4 episode "Thomas and the Special Letter" in the overhead shot of all the engines before Sir Topham Hatt reads the letter from the four year old girl.
Three real engines have been featured on the show, Stepney has made numerous 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".
Sir Ringo Starr was famous for being the drummer for The Beatles who recorded a song titled "She Said She Said" which was about actor Peter Fonda. Fonda eventually starred in Thomas and the Magic Railroad (2000), except the role of Mr. Conductor in said movie, which Starr shared with George Carlin on Shining Time Station (1989) was played by Alec Baldwin.
Bobby Davro parodied the TV show in Rock with Laughter (1993) which he played Ringo Starr. In the sketch, Ringo Starr (Davro) narrates whilst roller-skating which other actors playing the characters also roller-skated and the sketch ended with Ringo Starr losing control and accidentally crashing into the camera.