The Danza: In Season 4, Danny Strong plays Danny Siegel, Jane's cousin.
Executive Meddling: Resulted in a six-month delay to Season Five. Contentious negotiations between AMC and Matthew Weiner eventually led to a deal which included shortening episodes by two minutes, increased product placement, and possibly trimming the cast.
I guess Jason Stackhouse isn't the only one Mrs. Newlin is trying to help find his way back to joy. And what the hell is Jane Bodehouse doing being Sally's psychiatrist?
Ken Cosgrove is the future son-in-law of The Devil.
John Slattery's real life wife Talia Balsam plays Roger's wife Mona. Rather amusingly, their characters get divorced so that he can marry a twentysomething.
Creepy little Glen Bishop is played by Matt Weiner's son.
Romance on the Set: Alexis Bledel (Beth Dawes) and Vincent Kartheiser (Pete Campbell) played two people in an affair in Season 5 (early 2012), officially started dating in October 2012, and got engaged in March 2013.
Star Making Role: For practically everyone on the show since the majority of the cast were unknowns or only known on niche shows before the series launched. The notable exception is Robert Morse, who has been a name for decades.