It was actually by happenstance that I took notice of this, for I was moving right by the photo until I noted the deacon. You will note the distinctive way that the deacon in the Ambrosian rite wears the stole outside of the dalmatic -- and then of course, once that grasped my attention I noticed the special vestment around the neck of the deacon and subdeacon and the form of the alb, also part and parcel of the Ambrosian rite.
Of course, another distinctive feature is that you will note that unlike the Roman rite, the subdeacon is to the right of the priest-celebrant and is not wearing the humeral veil and holding the paten. In the Roman rite, he would be kneeling directly behind the celebrant a few steps down, while in the Dominican rite, he would be kneeling where he is, but still with the veil and paten. The Ambrosian rite is one of the few rites where one does not seem to see this feature. Whether it was ever a feature of the Ambrosian rite, I am uncertain.
