Agreed! The transition from "Denise speaks like normal girl" to "Denise is insensitive and speaks with a kinda low voice" occurred during this episode, when she had already been behaving in an insensitive manner from the beginning of the season.
Yeah, it's weird. While the episode that did air first had signs that it was actually intended to be first (J.D. pointing at the ABC bug and declaring 'that's new', the Neilsen family bit at the end), this seemed to introduce the interns (with the "premiere" episode also introducing them... odd), introduced the reason for Elliot and Katie having that talk a few episodes ago (which I believe was one of the ADR lines - a shot where you couldn't see Elliot's face but heard her say "now that Katie not a jerk..." - the other line being a similar 'don't see her actually speak it' line about her and J.D. being together but it being a secret, which was completely invalidated by it not being a secret in the next episode).