When I saw the suspected error before the meeting I spoke to one of the guys. He said I absolutely cannot mention the issue right away. He helped me workout a couple of questions I could ask to nudge them in the right direction.
When the meeting started the Director of Infrastructure, some people of the accounting department and a couple of the IT people supporting them were shouting at each other and trying to find the one responsible for the fault(this bug actually cost them a couple of millions).
I interrupted them by saying I don't care who's responsible and asking the questions I rehearsed. The director of infrastructure who was supporting the accounting people then found the issue(he retired a year later and yes weird structures in that company).
Anyway, the guy was really proud and the accounting department was praising him and the blame each other games stopped until ...
... I had my 1on1 a while later and the CIO told me that he heard I was yelling at people in that meeting.