Aside from being one of the funniest (and still, strangely underrated) shows on television right now, Scrubs has always been a series that pushed its boundaries. For viewers, NBC's mistreatment of the show has led to greater creative risks. Held off to be a winter replacement, the sixth season took that mandate to heart, with creator Bill Lawrence taking off the restraints.

Some of the season may be a little uneven in its treatment of the main characters. Certainly, Dr. Elliott Reid (Sarah Chalke) went from quirky to out and out insane, though every other character took it all in stride. But that also allowed for her fiancé, Keith Dudemeister (Travis Schuldt) to deepen as an important part of the cast.

Other elements strengthened. More supporting cast members built up, in what Lawrence calls "the third tier" of characters in one extra on this set. Interviews with these bit players, background extras that have grown into being essential parts of the Scrubs madness, make it clear that this is a special production.

Then there's that musical episode. With some songs from the composers of Avenue Q, the episode moves series subplots along, stays true to characters even in song and has a fairly reasonable (if not scientifically plausible) explanation for the music. A true high point for the series, it's no wonder the disc extras spend more attention on this episode than any other.

For me, a personal favorite among the extras is seeing alternate takes of Neil Flynn's Janitor. Largely left to his own improvisational devices in the script, Flynn rarely fails on his end, and as the disc shows, often has two or three great riffs from the same launch point.