Mitchell mentions how it's all "very Chinatown". He refers to the big twist in that classic movie that Faye Dunaway's character is both the mother and sister of her father's grandchild due to incest.
Final appearance of Rachel Bay Jones as Dylan's mom Farrah.
Haley, Alex, Lilly, Joe and Dylan are all absent in it.
The title is a reference to the phrase "three's a crowd".