In a poignant scene of 1933 WWI film The Eagle and the Hawk (not to be confused with the same-name 1950 western film), while the pilot played by Fredric March performs a loop-the-loop in his – I believe – Airco DH.9 (is that correct?) to evade a German opponent, his observer/gunner falls out of his place and plunges to the ground (he had already been hit and probably killed by the German, but the pilot wasn't aware of it, so this is a real trauma for him).
See the scene here, starting from about 57:25.
Besides the dramatic value of this scene within the narrative, would such a fall as the gunner's be realistic? If those aircraft were capable of such manoeuvres, wouldn't the crew be somehow secured?