Character mistake: Throughout the episode, a "Bufferbeam" is referred to as "a buffer." Also, at the beginning, the narrator says that the diesels are shunting coal trucks when they are really shunting flatbeds.
Revealing mistake: In a shot of Gordon arriving at Brendam Docks, only half of his tender is visible.
Thomas and the Sounds of Sodor - S16-E11
Deliberate mistake: When the engines are performing "The Sounds of Sodor", Emily, Thomas, Percy and Gordon have the correct whistle sounds but at a lower pitch. At one point, James has Emily/Henry's whistle sound, Mavis has her old "New Series" horn, and Thomas has James' whistle sound.
Continuity mistake: When Thomas hides behind the trucks, there are only 3. But in the next shot, there is a flatbed with a crate on it in front of the trucks.
Kevin's Cranky Friend - S17-E1
Audio problem: James and Henry swap whistle sounds throughout this episode.
Kevin's Cranky Friend - S17-E1
Continuity mistake: Throughout most of the episode, Cranky's ladder is on the wrong side.
Kevin's Cranky Friend - S17-E1
Continuity mistake: After Sir Topham Hatt leaves the docks, Henry disappears.
Continuity mistake: At the beginning of the episode, Henry is pulling trucks and Hiro is pulling nothing. In the next shot, Henry is pulling nothing and Hiro is pulling flatbeds.
Continuity mistake: UK Only: When Luke is coupled up to Skarloey's train, he has 5 trucks and a white brake van. When the deer jumps in his cab, the brake van disappears. And when Luke is heading towards the Castle, he has a brown brake van.
Revealing mistake: When the elephant is loaded into the truck, the tracks abruptly end behind Charlie.
Santa's Little Engine - S17-E18
Revealing mistake: At one point, the shading effect on Thomas' whistle is not rendered properly, so it appears silver instead of gold.
Santa's Little Engine - S17-E18
Continuity mistake: The sleigh leaves tracks in the snow behind when it slides down the hill. When Thomas races towards the sleigh, the Snow Tracks disappear.
Revealing mistake: Each time when Thomas takes a shortcut, the points do not change.
Factual error: When Bertie finds Thomas derailed, Bertie is on the wrong side of the road. The UK drives on the left. Also, Thomas runs under North American directional rules at the beginning and end of the episode.
Character mistake: UK Only: When Thomas comes back to Annie and Clarabel, he calls the latter "Carabel."
The Afternoon Tea Express - S17-E26
Continuity mistake: In the shot of Stephen at the dairy, one of the trucks is in the front and the other one is at the back. But in the shot when Stephen is out and about, the first one is at the far back and the other truck is at the front, but later, the trucks go back to their original positions.
Audio problem: In the first shot, Duck's chuffing sound doesn't match his speed.
Revealing mistake: Duck's footplate clips through the platform at Knapford at the beginning.
Duck and the Slip Coaches - S18-E8
Audio problem: At the beginning, Edward has Thomas' whistle sound.
Continuity mistake: Throughout the episode, rust stains disappear and reappear on Duncan's front buffers.
Answer: He was in the water.