"More seriously, some of Toland’s accounts of Kane swerve close to deception. [...] the first image was accomplished by means of a back-projected film showing the boy Kane in the window, while the second image is a multiple exposure. The glass and medicine bottle were shot separately against a black background, then the film was wound back and the action in the middle ground and background were shot. (And even the middle-ground material, Susan in bed, is notably out of focus.) I suspect that the flashy deep-focus illustration in Life, shot with a still camera, is a multiple exposure too. In any event, much of the depth of field on display in Kane couldn’t have been achieved by straight photography."What I draw from this is that in trying to say that the shot was created through deep focus they're actually hiding a bit of magic which is just as exciting. They're using a kind of matting process in mundane domestic situations that would usually be used in far more fantastical situations, such as making a spacecraft fly.
It's also interesting that actually they're not doing anything here which the maker's of Michael Palin's new documentary have recently been kicked about the park for (see here, next to bottom). It continues to be true that people won't accept techniques used in a fictional setting within a documentary even though often they share much the same artifice.