The money dies with Marion

The $40,000 that drives the entire first act of Psycho (1960) goes into the swamp inside a folded newspaper on the seat of Marion's car — unnoticed by Norman, never recovered, never mentioned again. The audience watches the film's ostensible subject sink.

This is The MacGuffin demonstrated with unusual honesty: most films at least pretend their MacGuffin mattered. Psycho lets you see the pretence dissolve — the money existed to move Marion to the motel and to aim the audience at the wrong genre (crime-and-flight thriller), so that Killing the protagonist at minute 47 lands on an unguarded flank.

Detail worth teaching: Hitchcock holds the sinking car's pause just long enough for the audience to catch itself siding with Norman — the Point of view transfer, measurable in one shot.