like how people eating in the model home eat the only two things in the fridge: mustard and parmesan cheese.
the "Sound of silence" jokes.
Tobias: "daddy wants to get his rocks off".
George Michael and Michael calling each other back and forth pretending to be in the same fake traffic jam. (this plays WAY better in the remix btw)
the restaurant on the barter system (didn't even properly notice this until I watched the remix)
I think S4 would have been a bit stronger if they had followed through on their original idea of being able to watch the episodes in any order. But I get why that wasn't actually feasible.