You didn't miss anything, az. Like most long running series, Big Bang has a number of continuity errors. I think they've had 2 or 3 different street addresses. There are others that I can't recall just now; most of them about Sheldon.

Whenever the subject of dancing comes up, Sheldon confuses me.

S1E03 "The Fuzzy Boots Corollary":

Leonard, Howard, Raj and Sheldon take salsa lessons.

S1E07 "The Dumpling Paradox":

Sheldon said: "Ok, assuming we could dance, which we can't..."

S3E03 "The Gothowitz Deviation":

Sheldon said: "Penny, while I subscribe to the many worlds theory which posits the existence of an infinite number of Sheldons in an infinite number of universes, I assure you that in none of them am I dancing."

S4E21 "The Agreement Dissection":

Sheldon said: "No, thank you, but for the record, I’m an excellent dancer. Proficient in the rumba, waltz and cha-cha."

@az51316 said:

So in the latest episode, Sheldon says he has no idea how everyone found out about his sex life since he only told a handful of people, implying that he doesn't understand the concept of spreading rumors/gossiping. However, a few years ago he and Amy made an experiment telling Penny they had sex and got pregnant for the purpose of figuring how fast rumors/gossip is spread. It's gotta be an inconsistency, or did I miss something? Can someone please clear this up?

Another consistency issue is about pets. Leonard and Sheldon have both at least started to go down the road of getting one or more cats, and Sheldon actually did so, although we're told at other times that the Roommate Agreement doesn't allow pets.