Actually that night is shown as a memory of Eric in the future episodes. Brooke and Eric talked about it. And as i remember it they were back form a party where Brooke had too much wine and almost fall on the bed. It was not shown as she was thinking it was Ridge nore that she drank at home. I am not sure if i remember well will see.
From what I've read online, Y&R began in Australia in 1974 and in New Zealand in 1977 and the episodes started from the beginning in both countries. Did the Australian broadcasts have breaks and that's how they ended up more than one year behind?
Blog post about Y&R's broadcast history in Canada: MarkH's Soap Musings: Canada: Why does Y&R have a late timeslot and day-ahead episode? (markhsoap.blogspot.com)