Actually, If you are asking if a soundwave LIKE thunder could hit a mirror, no it wouldn't reflect it. The mirror would shatter and just maybe a little sound would be produced but, not much. The shatter would be louder than the sound of the produced sound.
come on guys, couldn't you figure out he didn't mean the sound.
Anyway. the way our eyes see mirrors is a reflection of light and lightening is much more than light. Im not totally sure if glass is a conductor but if it was lightening wouldn't reflect off it. it would either pass down it or not pass through it at all. Lightening is electricity. Its just a lot of it.