Other mistake: When the train stops Godfrey gets off to relieve himself but when he is climbing back in to the carriage the train appears to be already moving at speed because the background projection started moving too early.
Other mistake: Wilson picks up the empty tablet bottle, but we hear the tablets rattling inside. Wilson then says 'it's empty, sir.'
Other mistake: The Church Hall got through an impossibly large number of different pianos, especially considering the fact that there was a war on.
Battle of the Giants! - S4-E14
Other mistake: Mainwaring hangs his new cap on a hook on the inside of his office door, the rest of the platoon are having bayonet practice in the hall. Pike is running with the bayonet but misses the dummy and his bayonet goes through the office door and Mainwaring's cap. The bayonet only goes through the cap once, but there are two tears in the cap.
Other mistake: Walker is attempting to steal items from the farm but appears on the training activity with the other troops at the same time.
Answer: The show is a comedy, this was played for comedic effect and to show that in times of extreme fear, in this case about to be crushed by a steam train, the men had an adrenaline surge strong enough to pedal fast enough.