10/06 - Expect to see a home movie of Seth's Bar Mitzvah, which took place 5 years ago. Source: SpoilerFix.com
10/04 - Julie shares her disappointment in herself for lying to Marissa with Dr. Roberts. There is a party (Ryan's Bar Mitzvah?) at the Newport Country Club. The Cohens, Johnny, Marissa and Summer are in attendance. Ryan seems to be jealous of way may (or may not) be going on between Marissa and Johnny. Source: SpoilerFix.com
09/01 - "Ryan, this year for Chrismukkah, is going to have an honorary Bar Mitzvah because, you know, every Jewish boy wishes he had Christmas and Seth has given himself that, and every gentile wishes he had a Bar Mitzvah. Now Seth wants to give that to Ryan." Source: Kristin on E!Online
08/24 - Josh Schwartz: "The last day of Hanukkah this year lands on Christmas, so Chrismukkah actually takes place in the [real] world." In The O.C.'s world, Chrismukkah takes place in the 10th episode. Source: Ask Ausiello @ TV Guide