Eureka is evolving. This is the first time we've seen a fully autonomous anthropomorphic robot show up. Sarah is mostly autonomous of course, but she is stuck to the house.
I did like how they played it. At first I thought they were going to make the robot the bad guy. However, what they did was so much more bittersweet. They made him one of the good guys, and they made him grow and learn. That's how robots should be. And all without a single mention of Asimov's three laws of robotics (which are stupid for other reasons, but that's a discussion for another time).
I hope Andy remains a part of Eureka showing up at odd moments and helping out. However, they shouldn't keep him in a box and then just haul him out to do the heavy lifting. That would be mean.
It was also very evident that a high school education in Eureka, even for someone of regular intelligence, pays off better than public school. Zoey knew how to make a gravity bomb out of tenser field. Way to go girl. I wonder what she's going to choose about college. Is there a college in Eureka? I would think there would be.
I also liked the evolving pregnancies of the show. Though the fact that they have two going at the same time is a little hard on the suspension of belief. Either that or I'm a conspiracy theorist and I want them to be doing something Eureka-ish with the babies. Poor babies.
They also introduced the season arc at the very end. It was just a blip. Did anyone else catch it?
Aliens. At least that's what we're supposed to assume of course. The radio antenna array goes wonky, and then Henry says "We don't have anything out that far. ... It's coming straight for Eureka." Yeah, that just screams aliens. Which means of course that I doubt it's actually aliens. Maybe it's a project from Eureka's past. Sort of like the Stargate Episode (110) The Torment of Tantalus when they actually sent out a ship long before they should've been able too. Yes that's reminiscent of last season's big secret, yet at the same time it's so different.
Of course I could be wrong, and it might actually be aliens. In which case, the secret for this season will be that we've had contact with aliens before.