The question I would have in this case is who made that decision for Ferris' character? Was that scripted? Something the director added, something Broderick did

The question I would have in this case is who made that decision for Ferris' character? Was that scripted? Something the director added, something Broderick did? As was mentioned elsewhere, everything seen on film is (mostly) intentional. It was either decided to be put there, or decided to be left in (even those goofs where the camera is seen, someone probably saw it in post and decided "not worth fixing"). Sometime actors and have some autonomy with their characters, similarly directors can have great flexibility in the rendering of the story. So, anyway, when you seem moments like that, always curios where they come from.