When Lorelai goes into the bakery she says, "Hi Sue, I'm here to pick up the cake," but then leaves without any cake.
In this episode, Paris hates when people get emotional at goodbyes but in the episode, Last Week Fights, This Week Tights (2004), Paris gets really emotional at the end of the year.
Logan describes what happened at his graduation. Rory was there, so she would already have known what happened.
Before Emily and Richard sing to Rory, Emily says, "Please excuse us. We're not singers." However, the fact that Richard is a singer has been mentioned several times throughout the series. It is mentioned more than once that he was part of the Yale "Whiffenpoofs" and sang in a barbershop quartet in Season 5.
Milan Kundera's name is consistently mispronounced during this episode. (The stress always falls on the first syllable of the word in Czech.)
When discussing the 4 ticket maximum at Rory's graduation from Yale, Taylor asks if there are no children of divorce, insinuating that children of divorce would need less tickets. Both parents of children of divorce would still want to see their kid graduate, and could possibly need more tickets if they have remarried.