The Sad Story of Henry - S1-E3
Audio problem: When James is about to puff away from Henry's Tunnel, if you listen closely, James is heard puffing before he has even left. (00:01:00)
Other mistake: When Thomas is uncoupled from Annie and Clarabell he has Percy's face.
Other mistake: At the start Gordon's buffers are crooked.
Continuity mistake: James and Edward are on the mainline at first, but then they overrun the platform at Dryaw station, which is on Thomas' branch line.
Audio problem: In the 1992 "Thomas Gets Tricked" VHS release, the music stops and a man's voice says, "Look out for the train!" when Thomas climbs up Gordon's Hill. The voice can still be heard in the 1995 release, but the music does not stop.

The Sad Story of Henry - S1-E3
Revealing mistake: When the passengers try to pull Henry out of the tunnel, they have putty on their feet. Sir Topham Hatt's hand is also purple.
Continuity mistake: When Thomas is organizing the trucks, in a second close-up of a truck, the background disappears in mid-sentence.
Edward, Gordon and Henry - S1-E4
Visible crew/equipment: When Gordon backs on to the siding, you can see the inside of his cab, which is just some equipment.
Edward, Gordon and Henry - S1-E4
Other mistake: When Gordon leaves the station, he has two brake coaches, even though express trains are suppose to have one.

Continuity mistake: The sign says: "Danger - engines must not pass this board." When Thomas passes it, "board" is replaced with "point."
Thomas and the Breakdown Train - S1-E7
Revealing mistake: In the scene of James' wheels sparking while passing Tidmouth Sheds, a metal rod is igniting the sparks from his wheels.
Other mistake: In a close-up of Thomas, Annie and Clarabel are nowhere to be seen.
Visible crew/equipment: In the opening shot of the restored version, studio equipment is visible in the top-left corner.
Visible crew/equipment: As Henry crashes into the goods train, a crew member's hand can be seen pushing him.
Edward, Gordon and Henry - S1-E4
Other mistake: When Gordon is sent to the siding after breaking down, he passes the set of points needed to cross over to the other line.
Continuity mistake: Gordon's connecting rods change position after he pulls Thomas out of the mine.

Visible crew/equipment: In the shot of Thomas rolling backwards onto the turntable, look left very carefully, and you'll see a camera tripod visible. Fullscreen version only.
Continuity mistake: Before Percy Runs Away, his crew is out of the cab. But after Percy Runs Away from Gordon, his crew is back in the cab.
Continuity mistake: In a close up of the tar wagons before James crashes into them, James disappears.
Visible crew/equipment: When James crashes into the tar wagons, a finger can be seen in the bottom right-hand corner.
Answer: Breakdown trains help the engines back on track.