Production sources tell TMZ, host Chris Harrison held a powwow with the cast on the first day back to film the show after the Warner Bros. probe concluded there was no sexual assault ... and the cameras were rolling as he took people back to the Corinne Olympios/DeMario Jackson sexual escapade in the pool.

We're told Harrison dramatically recounted how a producer expressed concerns and it turned into a full blown scandal. After taking everyone through the investigation, he paused, then asked the cast if they were comfortable continuing, and gave them a chance to pack up and leave.

To absolutely no one's surprise, everyone stayed, drank and even banged in the boom boom room.

Lemonade ... it comes from lemons.