You're throwing around the word "audit" far too casually. In all likeliness, you and your friends were not audited. The CRA probably asked you to submit supporting documents such as receipts and other written records to prove your claim, as you are legally required to do.

An audit is much more severe and generally involves an in-person interaction and seriously combing through all your accounts and transactions. https://www.canada.ca/en/revenue-agency/services/forms-publi... , https://www.bnnbloomberg.ca/what-s-the-difference-between-a-...