Toby and the Stout Gentleman - S1-E21
Revealing mistake: The water is not flowing when Toby passes Arlesdale Lake.
Revealing mistake: In a close up of Thomas' driver, his cap brim is falling off and he has a hole in his head.
Revealing mistake: In a close-up of Thomas at the beginning of the episode, his wheels aren't moving for 2 seconds. This is easier to see in the restored version.
Revealing mistake: In the first close-up of the policeman, the camera wobbles.
Revealing mistake: When Gordon is being pulled from the pond, in the close up scene of Gordon reversing up the sleeper bed, the front of his buffer beam/running board catches on the upright stake to the right hand side of the worker figure, pulling it back before it rights itself. (easier to see on widescreen version). (00:04:10)
Revealing mistake: When Gordon falls into the ditch, wires under his cab are visible.
Revealing mistake: When the boys sing, the camera shakes.
Revealing mistake: When Gordon puffs into the ditch his face looks wonky and wires are visibly attached to his cab.
Thomas' Christmas Party - S1-E26
Revealing mistake: In the very last shot of the episode, loads of wires are visible in front of the engines and behind the turntable.
Thomas, Percy and the Coal - S2-E1
Revealing mistake: In some shots of Thomas and Percy, both engines have wonky eyes.
Thomas, Percy and the Coal - S2-E1
Revealing mistake: When Toby pulls Annie and Clarabel, the latter coach has a loose roof.
Revealing mistake: After Gordon stops on the bridge for the cow, his wheels keep moving for 3 seconds.
Revealing mistake: When Percy stops on the bridge, white glue is on his middle lamp iron.
Revealing mistake: Edward has wonky eyes in some scenes.
Revealing mistake: When Edward is at the last station, his whistle is crooked.
Revealing mistake: In a close up of Percy's driver, he is in Henry's cab.
Revealing mistake: When Percy is at the "backing" signal, his cylinder is sagging.
The Runaway - S2-E10
Revealing mistake: When Thomas' fireman is ill, you can see a brief flash of red outside, meaning it's James. (Note: same footage from Old Iron).
The Runaway - S2-E10
Revealing mistake: When Duck comes to Terence's field, the end of the track leads right into the bushes right behind duck.
The Runaway - S2-E10
Revealing mistake: When Duck is happy at the beginning, the breakdown train's buffer on the right is broken.
Answer: He was in the water.