At the Blue Mountain Quarry, Thomas meets a little engine called Luke, who's been hiding because of a big secret.
Blue Mountain Mystery contains examples of:
- Big Damn Heroes:Thomas rolls out of control and ends up dangling precariously off a cliff. Luke hears his cries for help and manages to haul him to safety.
- The Bus Came Back:
- The narrow gauge engines (sans Duncan) return since the twelfth season.
- Annie and Clarabel speak for the first time since the eleventh season.
- By the Lights of Their Eyes: Luke's eyes light up as he is hiding in the tunnel.
- Cold Open: The first Thomas and Friends production to begin with such.
- Creative Closing Credits: The titular song plays over the end credits, as they scroll over a montage of scenes from the movie.
- Digital Destruction: Some US DVD releases are slowed down and add an extra two minutes; thus audio is distorted. Averted with the iTunes release.
- Musical Chores: "Working Together" plays as Thomas works with the narrow gauge engines.
- Mythology Gag: After Luke drags Thomas back to Owen's platform and he comes crashing down, his eyes spin around rapidly. This is a reference to the live action model animation, where the engines' eyes frequently spin around if excited or shocked.
- Out of Focus: The rest of the Steam Team. Gordon doesn't even speak. Averted with Toby who normally suffers from this. Even if his role is simply to look after Annie and Clarabel while Thomas is at the quarry.
- The Reveal: We learn how Victor came to Sodor.
- Sent Into Hiding: The plot revolves around the Narrow Gauge engines keeping a lost engine, Luke, secret from the Thin Controller (due to supposedly killing another engine via an accident said engine was found and repaired as Victor, who resolved everything when he found out). How this is managed isn't quite elaborated upon, since the engines (including Luke himself) are pretty much completely reliant on workmen to function
- Shout-Out: "Blondon Bridge is falling down!"
- The Stinger: In the middle of the credits, Thomas stops at the Steamworks, where Luke and Victor surprise him by giving Rheneas a yellow paintwork.