When Merrill is first talking to Christian, reference is made to Madame Rose, killing a girl and Merrill trying to cut Christian's face off. This all happens in the Season 2 episode Oona Wentworth.
Julia and Sean like to have make-up sex in their children's rooms: Conor was conceived in Matt's bed at the beginning of Season Three, and in this episode they had sex against the newly-painted wall in Conor's room after Julia admitted to her affair with Marlowe.
It's revealed that Michelle is 30 years old.
Christian mentions 'a woman who won the lottery' who paid him four hundred thousand dollars for sex – this happens in Dawn Budge (the woman being the title character played by Rosie O'Donnell)
When Sean suggests Christian picks someone up from a bar, Christian replies 'no risk there, just ask Lizzie'. This refers back to Shari Noble where Liz met a girl in a lesbian bar, went home with her and ended up having her kidney stolen.
When Sean suggests Christian picks someone up from a bar, he mentioned 'another mother-daughter team'. In the season opener, Cindy Plumb, Christian slept with a mother and daughter that he met in a bar.
Liz mentions Mike Hamoui, the surgeon (played by Mario Lopez) that Christian had liposuction off in the episode entitled Monica Wilder.
It's revealed that Mrs. Grubman's first name is Hedda.
Mrs. Grubman refers to Christian being in her bedroom under 'slightly different circumstances' and also regretting that she didn't sleep with him when she had the chance. This refers back to the Season 1 episode Nanette Babcock where Christian- under duress from Sean- offered to sleep with her if she would drop a lawsuit against McNamara/Troy.
Christian's suggestion on dealing with Burt involves 'a 12-gauge and a bunch of hams'. This refers to the Pilot episode when they get rid of Silvio Perez's body by weighting his body with hams and dumping him in the Everglades.
When Dawn is having her initial consult with Sean and Christian, she mentions Dwight and Mallory, her husband and her daughter who were seen in the episode Dawn Budge.
As Sean and Christian do the surgery at the start of the episode, reference is made to the episode Blu Mondae, where Christian did pro-bono work on the title character after sleeping with her.
It's revealed that Sawyer's first name is Marlowe.
Julia confronts Sean about calling a sex line. Sean then explains about giving a phone sex operator a voice-lift; this was the featured procedure in Season 4 opener Cindy Plumb.
When Sean and Christian are talking about Matt picking up rubbish, Sean says 'at least he's not dating Nazis or transsexuals anymore', referring to Matt's previous girlfriends- white supremacist Ariel (Brittany Snow, Season 3) and secret transsexual Ava (Famke Janssen, Season 2).
Dawn mentions that she was on Maury after she won the Powerball lottery. Maury has never had a show featuring lotto winners.
It's revealed the mysterious woman (who kisses Michelle) is named James.
Julia tells Sawyer about almost having had an abortion. Julia and Sean were at the abortion clinic in the season 3 episode Joy Kringle.
Liz says that Christian's sex tape was on Youtube. This is almost impossible seeing as Yotube doesn't allow porn to be upload. It's possible that it may have been temporarely on Youtube, but the video would have been flagged and taken down before it reached 6,000 views or downloads, as Liz stated.
There is no way Christian could be unaware that he was being filmed. The video, as uploaded, was cut together from several different angles -- a few directly from the woman's point of view and one seemingly from his own.
In the show, of course, he was more worried about how he looked in the video rather than the fact of its existence, but he did seem more or less thrown by it.