A vehicular mirror reflective element sub-assembly includes a mirror reflective element and a mirror back plate. A heater pad is disposed between the mirror reflective element and the mirror back plate. The heater pad has a light transmitting portion that is generally aligned with an aperture of the mirror back plate. The mirror reflector includes a light-transmitting portion thereof that is generally aligned with the light transmitting portion of the heater pad. An indicator module includes a housing, and a circuit board is disposed in the housing and includes at least one light emitting diode. When an equipped exterior rearview mirror assembly is mounted at the side of the vehicle and with the light emitting diode activated, emitted light passes through a light diffuser and through the light transmitting portions and exits the mirror reflective element to provide a visual icon visible to a driver of the vehicle.