Palm Springs
The setting of Palm Springs is a metaphor for the fact that this family's love is in a desert. Nothing has grown in years between them.
Hypocrisy
Silda has helped Brooke in writing her memoir by ensuring the facts of what Lyman and Polly did are correct. This is a metaphor for her hypocritical nature as she betrayed Brooke by not revealing she didn't help Henry when he asked her to.
Writer
Brooke has become a writer just like her mother Polly. This is a metaphor for though their relationship is deeply strained, that the two women are truly alike in their beliefs and tactics in life.
Reality TV
Tripp produces a reality TV court room show that Brooke won't watch. His show is a metaphor for how his view of reality has been warped by this deep family secret his parents have keep since he was five years old.
GOP
Lyman and Polly joined the GOP and moved to Palm Springs after giving up careers in show business, and they kept up their party politics through Henry's apparent suicide. This is a metaphor for them paying any price in order to protect their son.