Here is a possible scenario:
The Captain - who we have learned was generally difficult and autocratic and did not fly by the book - is for some reason, (maybe hunger), in a particularly bad and unapproachable mood that day. Due to his impatience, he decides to accept an approach that is too close, too high and too fast, instead of simply asking for more track miles or even a 360°
He barks orders to his F/O who is either brand new or timid or both. This shouting and the extreme approach puts the F/O behind the aircraft trying to keep up with the orders and checklists and seating the cabin crew and radio calls, so he has no time to think except to do what the Captain is ordering. Captain barks "Gear down" 30 nm out and the F/O complies, his mind paralysed. As they get to short finals the Captain - who has forgotten the gear is already down - barks "Gear Down" and the F/O moves the lever, but because the gear was already down he actually raises the gear. As they flare; the F/O realises what has happened and miserably, finally manages to speak up and calls go-around to avoid a crash landing.
The Captain at last realises that he has severely f****d up and hasn't got away with it this time, so he obeys the go-around call, hoping he can rescue the situation and be able to explain the disastrous approach away somehow. But then the engine accessory gearboxes and oil pumps are badly damaged and the subsequent fatal accident is inevitable.
This is the sort of thing that F/Os need to be able to deal with, (and all Captains need to be aware of), but in years of CRM courses, I have never seen it properly addressed. Cabin crew are given specific training and role playing about how to deal with angry or unreasonable passengers but I have never seen F/Os trained to deal with angry or unreasonable Captains.