Character mistake: The narrator says, "some trucks were left behind", but only 1 truck was left behind.
Continuity mistake: At the beginning, Edward is pulling 5 cattle trucks. When he approaches the cows, he is pulling 4 cattle trucks.
Continuity mistake: Gordon's express train has 1 composite coach and 2 brake coaches when he passes through Wellsworth station. When he crosses the viaduct, he has 2 composite coaches and 1 brake coach.
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.
Continuity mistake: Gordon can be seen next to Edward when Edward says "two big engines afraid of a cow?", but Gordon should have been on the turntable.
Revealing mistake: Edward has wonky eyes in some scenes.
Answer: He was in the water.