A mirror reflective element sub-assembly includes a mirror reflective element, a mirror back plate and a signal indicator. The mirror back plate includes (i) a generally planar portion and (ii) an indicator receiving portion. The indicator receiving portion has a wall structure extending at an angle from the generally planar portion adjacent to an aperture established through the mirror back plate. The signal indicator has a light source disposed at a circuit element and a housing substantially encases the circuit element therein. An electrical connector protrudes from the circuit element and is accessible at a connector portion of the housing for connecting to electrical wiring of the vehicle. The signal indicator includes an indicia element at a forward end thereof. When the light source is activated, light emitted by the light source emanates through the aperture and through the mirror reflective element and is transmitted through the indicia element.