Plot hole: How could Gordon's driver tell the station master that Gordon couldn't get up the hill? There are no phones on Gordon's hill.
Visible crew/equipment: When the banner hits Gordon, in the next shot, a scaffold is very visible in the trees on the right. (Visible in Wide screen version only).
Audio problem: Before Emily goes into the duck pond, her brakes are heard screeching but her wheels are still moving.
Continuity mistake: At the beginning of the episode, the order in the sheds is Henry, Thomas, Gordon, James and Edward. But, when Thomas is complaining, the order is now Thomas, Gordon, James, Edward and Henry.
Audio problem: When Gordon backing down to the bottom of the hill, you can hear brakes screeching, but Gordon's wheels are still moving.
Continuity mistake: When Edward is pushing trucks over a turntable, when he stops, he is very close to the trucks, when the camera changes, he moves back a bit. (Note the tank the Fat Controller is standing on).
Continuity mistake: When Thomas teases James about bootlaces, the background disappears in a close up of Thomas.
Continuity mistake: When Gordon says "Yes, I will" the background disappears between shots.
Revealing mistake: At the end, when Thomas backs some coaches into the station, he starts moving after 3 seconds the camera starting rolling.
Revealing mistake: When Thomas passes the leveling crossing for a second time, the cars at the crossing have no drivers.
Revealing mistake: When Thomas goes back to the station to try again from the signal, when he starts, the steam is coming from the track and not from Thomas.
Revealing mistake: When Thomas passes a yard with a black car and a red car, you can see tyre marks on the ground from previous takes.
Revealing mistake: Just before Thomas goes over The Switch, his left eye is uneven and then when he crosses The Switch, it readjusts itself.
Other mistake: When the Fat Controller is talking to the crew, the buffers on the first coach in front of Thomas is crooked.
Visible crew/equipment: When the porter bangs the door, a light-stand is briefly reflected on the window of the door.
Revealing mistake: When Thomas leaves the sheds, his driver doesn't have a face.
Visible crew/equipment: When Henry is ill, one of the lights behind Henry is not one of the ones from outside, it's a studio light.
Other mistake: When Thomas is grumping, his lamp is dirty, even though he didn't do anything dirty yet.
Revealing mistake: At the beginning of the episode, the end of the set is visibly reflected of Gordon's smoke box in a close-up of Gordon.
Continuity mistake: When the engines are laughing at Thomas, Henry's eyes are wonky.
Answer: He was in the water.