As you go through an audit and you see links to other systems, you must be careful. Make sure you stay within the scope of the audit. I have seen auditors start to run to other departments to follow up on paperwork and such.
If the scope of your audit is limited, don’t go running around to other departments with a “Surprise! We’re here to check out some of your paperwork to see if it agrees with ….” If you do this you WILL make enemies! If that is your intent, which it sometimes will be, then give that department or person advance notice and formally include them in the scope of the audit.
ISO 19011 - Quality and Environmental Management Systems Auditing Forum Discussions