You'd still want to do code reviews after mob/pair programming though, because:

- the whole team might not be here and needs to review the changes to catch up.

- doing the wrong thing as a mob is still doing the wrong thing, and you may need more eyes on your code to spot that (especially if everyone during the session was convinced that what was written is right)

- IMHO, even if 10 persons were involved in writing it, a later review of the code can still improve quality (because people will actually be reading the code rather than writing it, which will expose other kinds of issues)