The glasses into which One-eyed Joe pours whiskey during his chat with Porter are not the ones used for the remainder of the scene.
When the track repair gang run out of the tunnel in front of the oncoming train there is a clear splice in the film between that scene and the train exiting the tunnel.
A railway wagon labeled "HOUGHTON" can be seen towards the end of the film. This is an English coal wagon from Houghton Colliery and could not have been seen in Ireland, thus revealing that the film was actually made in England.
The light bulbs in the bus interior set are standard mains voltage type, way beyond the capacity of a bus to power.
When the bottle with the message in it is thrown through the window of the stationmaster it enters from the left rear side of him striking the back of his chair and a second bottle is thrown in front of him landing in his plate.
When Harbottle moves the engine off its whistle is heard, but neither he nor Porter pull the whistle cord.
When they are trying to move a carriage which is blocking the main line Harbottle descends from the train with the shadow of the camera crew clearly visible on him.