[nznog] Can whois registrar info be wrong?

Hey all, Is it technically possible for the registrar details in whois (for a .com domain) be out of date, or is the whois the canonical source of the info? If it is possible, how would I go about finding out who's really in control? Does a registrar have an interface for that? Unfortunately I'm not sure how reliable my client's own records are on this ... Cheers, Richard