Boy was there a mountain of plot holes in this episode, not that it really mattered. "Chuck Vs. The Cubic Z" threw out any meaningful plot, and gave us an hour of pure, unadulterated fun. From an entertainment standpoint, the episode was a success, but on any other level, the episode was pretty lacking.
The episode features Stone Cold Steve Austin and Nicole Richie, reprising their previous roles, and Stacey Keibler as this week's CIA hot girl. Basically, the spy part consists of Hugo Panzer (Austin) chasing Chuck, Sarah, and Heather around the Castle after he escapes, and Heather (Richie) trying to convince Chuck and Sarah that their relationship is doomed to fail. There are a bunch of exciting, nonsensical fights and shootouts, making the episode a very enjoyable experience.
At the Buy More, there was yet another riot which gets completely out of control (Why didn't the spies handle it?), because of a game shortage (Again, why didn't the CIA get enough copies?). But it lets Big Mike provide support for Morgan, and take out Hugo Panzer.
On the relationship side, Sarah is rattled by Chuck saying that they might be next in line for marriage, but they come to an agreement by the end of the episode to take things slow. However, the final cliffhanger, as cheesy as it may be, shakes things up. There has to be consequences now, seeing as Chuck is holding the ring right in front of Sarah. Will Chuck propose? And if so, what do they tell Morgan and Big Mike? Surely they'd recognize the ring.
Normally, I wouldn't express my support for an episode so devoid of plot, but I couldn't help but be glued to the screen. Chuck is just too damn fun to not like.