What part would "カーブミラー" be, in reference to a car? (For context, the narrator is talking about an accident, and a cake flying under...something.) My instinct is just to write "cab mirror", but I don't know cars all that well, so I have no idea if that's correct or not.
Might this be the convex mirrors that they mount on posts on the sides of roads to help see around sharp curves? I dunno, that's a wild guess. Else I'd agree it's some wide-angle convex mirror on the car.