On the blackboard behind Ross when he's telling his students that he came up with the idea for Jurassic Park, it says that he was bitten by a mosquito and had a dream which led to the idea.
The Magna-Doodle in Joey and Rachel's apartment has a drawing of a Claddagh ring, which symbolizes love, friendship and loyalty.
Traditionally, if the ring is on the right hand with the heart facing outward, the wearer is not in any serious relationship and may be looking for a relationship. When worn on the right hand but with the heart facing inward, the person is in a relationship. A Claddagh worn on the left ring finger facing outward generally indicates that the wearer is engaged. When the ring is on the left ring finger and facing inward, it generally means that the person is married.
Ross tells Chandler that he should "just turn up and say the right name." This is a reference to Rachel running away from her wedding to Barry and Ross saying Rachel's name at his wedding to Emily.