Can you see a rainbow at night?

Yes, the moon is bright enough to produce a rainbow, and while rare, people do see it. We all just have to get out more at night. Since the moon is not near as bright as the sun, the rainbow produced by the moon at night is much weaker than a rainbow produced by the sun during the day. Our eyes see dim things as black and white, not in colour. So a night "moonbow" will look gray not colourful.