In the opening scene, when Alex and Haley are watching TV, it is showing the commercial Lily recorded in chapter 2x07 (Chirp).
Rob Huebel, who plays Phils arch nemesis, was actually considered for the role of Phil but turned it down. After the success of the show, he felt like an idiot.
Jay's birthday is on April 1st. In the finale of season 2, "The One That Got Away", the families watch a video edited by Luke. The date stamp on the parts of the video which were shot on that day ('Jay Pritchett: A life in words and pictures' and the skateboard video of Luke) show April 1st.
In the video Luke is using to put together the Dunphy kids' birthday present to Jay, there are clips from season 2. Haley is wearing the cat costume from Halloween, Luke has his space helmet from Chirp, Mitchell is practicing for the flash mob he will do in Manny Get Your Gun, Cam is putting on Fizbo's makeup for Lily's Princess Party, Claire has the speeding signs from Slow Down Your Neighbor, Phil is Bixby's Back and Gloria is screaming at Jay about the neighbor's dog from Unplugged. And she's sounding like a parrot.
For the first time, instead of Phil normally declaring "I've got Gloria!", he says, "I've got Claire!"