Three fun little things I've noticed. The first might be a mistake, although I'm not sure. The other two are, I'm sure, intentional, but so subtle I think some might miss them. Does that count as a hidden Easter egg?
The first, I've mentioned before in another thread, but I'll repeat it here. The script for "Sound of Silence" has Lois give Superman a rose, and Superman ask, "What's this for?" Lois asks if she needs a reason and he says he guesses not. I find it amusing to think that the final version was the result of Dean Cain missing his line and asking, "What's this?" and Teri Hatcher ad-libbing, "It's a rose," causing Dean to smile and repeat his line properly the second time around.
The second, which always makes me smile, is from "When Irish Eyes Are Killing". Two things, actually. The first is when Clark sits down at the table where Patrick is playing darts. Lois's wine class falls and Clark "super-catches" it before it hits the floor. He then sits down and sips some wine. I get a kick out of the fact that he is drinking from Lois's glass, sending a non-verbal message to Patrick. hehe.
The other thing that amuses me from this scene is that Clark throws the first dart with his left hand and the second dart with his right. Cracks me up every time.