When it comes to pronouns, it's typical to connect the pronoun to the most recently used noun. In your case, the "he" should have been "Mike", but it's not a great sentence to begin with. There are also better solutions, which some people have pointed out (lol, see below about this sentence - totally accidental).
When it comes to commas, those two general rules (item listing and additional information) are the most abstract forms of comma usage. When it comes to the words "which" and "that", however, there are special cases for each (both serve the same purpose in a sentence).
The word "that" should never follow a comma - ever. "Which", on the other hand, typically does follow a comma.
Code:
My coat, which is black, was tossed into the air.
My coat that is black was tossed into the air.
In short sentences, like the one you proposed, a comma does not necessarily have to be placed before "which", probably because syntax has changed over the course of several years. Anyway, hope this helps, because there is some other useful information in the previous posts as well.