When the anger is intense, the person with Asperger's syndrome may be in a 'blind rage' and unable to see the signals indicating that it would be appropriate to stop. Feelings of anger can also be in response in situations where we would expect other emotions. I have noted that sadness may be expressed as anger.
Why on earth do you carry a mirror around with you? It's purely a defensive device. We seldom quarrel, and this is one of the reasons. Can you imagine yourself getting all worked up and contorted and illogical and then coming face to face with yourself, looking at yourself exactly as you look to everyone else?