Last time on the DCU... the Justice Gang was late to the party. As far as I could tell those were the only changes made, everything else was a recap and "correct" as we knew it.

Also the orgy scene was great at setting and reminding the viewer of the tone of the show. It's serious, but also silly... and a little bit sexy.

Also Harcourt smiling after getting the shit kicked out of her. She's just as fucked up as everyone else.

Edit: I missed it on the first pass, but Supergirl is there too.