Continuity mistake: During the chase scene at the end of the film, P. T. Boomer (a character cut from the film), can be seen on top of Diesel 10 during the shot where he enters a tunnel.
Visible crew/equipment: In the shot where Diesel 10 races past Thomas and Gordon near the beginning, you can see a black pencil on the right of the screen.
Other mistake: The end credits show Annie, Clarabel, Bertie and Harold under the voice cast for "the trains", but Annie and Clarabel are rolling stock, Bertie is a road vehicle, and Harold is an aircraft, respectively.
Continuity mistake: When Diesel 10 is hanging, he's vertical. But in the next shot, he falls horizontally.
Other mistake: In a shot of Percy at night, James' tender is derailed.
Continuity mistake: After Thomas collects the coal truck and Lily praises him, it briefly vanishes from behind him.
Continuity mistake: After Diesel 10 is covered in coal, Henry is next to Gordon, then suddenly next to Splatter and Dodge.
Continuity mistake: After Thomas crosses over the collapsing viaduct, his steam disappears too quickly.
Revealing mistake: In a close-up of Thomas' wheels during the chase scene, they appear to be damaged.
Visible crew/equipment: When Thomas follows Diesel 10 from the sheds, the end of the set is visible.
Revealing mistake: As Thomas crosses the viaduct gap, a rope can be seen pulling him.