Regarding the earlier discussion re: "lost" commentaries, here's a list of ones I remember doing that never received a release. Keep in mind that there are commentaries that DID get released which I don't remember doing, so I'm probably forgetting plenty.
Lost commentaries later re-recorded and released:
A.I.: ARTIFICIAL INTELLIGENCE - One of our very first recordings, in fact I believe it was our second, recorded the same day as PHANTOM MENACE. Audacity took a massive shit and despite our best efforts the episode was unsalvagable.
DAWN OF THE DEAD '78 - We recorded a commentary for this film, but afterward felt that we could do better. The following weekend we did a new commentary for this film in a double-feature with the 2004 remake.
KICK-ASS - Recorded the same day as SUCKER PUNCH and SOURCE CODE, our first attempt to comment on this film imploded about mid-way through when the mixer came unplugged. Having already done two films and being an early party episode, we decided to cut our losses and just abandon the commentary.
TRON - We lost steam about 2/3 of the way through this commentary, crawling painfully to the finish line. Given that we felt we had plenty to say about TRON: LEGACY, we felt we needed to release something for the original, and we recorded and released a much better episode.
THE FRIGHTENERS - We recorded a full episode for this film which we were quite happy with, but the file became corrupted and when we went to release it we discovered two hours of silence in the file.
STRANGE DAYS - Originally recorded with guest commentator Eric Webb (if memory serves), our first attempt at a STRANGE DAYS commentary suffered a similar mysterious silencing.
Commentaries never released due to either technical error or simply not being up to snuff, not yet re-recorded:
HELLBOY
THE GREEN MILE
SAVING PRIVATE RYAN
GROUNDHOG DAY
PIRATES OF THE CARIBBEAN: DEAD MAN'S CHEST
THE TWILIGHT SAGA: NEW MOON
HARRY POTTER AND THE CHAMBER OF SECRETS
ZOMBIELAND
THE CURIOUS CASE OF BENJAMIN BUTTON
Those are all the ones I remember, though I'm sure there were more over the last four years, especially early on.
I was super tempted to bullshit and throw in titles like CITIZEN KANE and BTTF2 but I refrained.