Why does XKCD say that autogyros will crash if the pilot reacts to a stall as in a normal airplane?
That one thing is to unload the rotor too much (i.e. &quot;push on the stick&quot;):
From explainxkcd:

... Unfortunately, as soon as the rotor stops spinning, the whole aircraft falls like a brick and the rotor may be impossible to restart in flight. This is a situation that should be avoided at all costs.
Normally it is not a problem since the weight of the aircraft keeps the rotor spinning. However, if the weight becomes too low or even negative, the angle of attack will become negative, and the rotor will slow down and eventually stop. It can happen when the pilot &quot;pushes on the stick&quot; and dives.
Unfortunately, &quot;pushing on the stick&quot; is also how you escape a stall in a fixed wing (normal) airplane as it is a way to regain airspeed. This is actually a counter-intuitive maneuver but because a stall is an emergency, pilots are trained to do it instinctively. It can trick a pilot trained in fixed wing aircraft into doing the one thing that shouldn't be done on a gyro.