This happened to me recently. This is what worked for me: Email the journalist privately (not via the post's comments). Say you've found a small error. Explain

This happened to me recently. This is what worked for me: Email the journalist privately (not via the post's comments). Say you've found a small error. Explain it and its fix. Then apologize for not being clear in the first place (which is at least a teeny bit true). Close with an invitation to talk by phone or email or Skype. The two journalists I got in touch with were super friendly and nice. They genuinely cared about being correct.