Figure this could be interesting to see what dvds/blus have R rated level swearing, nudity ect during the commentary/docs during movies that are PG-13 or less. Examples i could think of
Daredevil (MSJ swears up a storm, and there are a bunch of F words during the documentaries on the second disc)
Dude Where's My Car
Jersey Girl

Kind of a cheat but Family Guy is rated TV-14 and constantly has sweary commentaries.

Didn't the Finding Nemo commentary have a bunch of profanity from a few people albiet bleeped?

I believe the Criterion edition of "Armageddon" had some profane behind the scenes footage and commentary track.

Behind Enemy Lines... it wasn't so much the swearing but the content and visuals...

"Red Band" trailers are only supposed to be shown with R-rated movies, but I've seen a few included on discs of PG-13 movies. In fact I've even seen a few VHS movies include them.

Phantom Menace-A couple of F-bombs delivered by Rick McCallum and Ewan McGregor on "In The Beginning".

Love & Basketball-Director Gina Prince-Bythewood on both commentary tracks. She even stops to "Sorry, Mom" for the cursing at one point.

Honorable mention:

I think the movie's too old to be rated (I'm referring to The Ghastly Ones) but one of the co-stars appears on the commentary. You will NEVER hear an old man cuss up a storm the way this fellow does!

Lower on the scale, but "Shit" has been mentioned on some "Simpsons" audio commentaries...

John Fricke recounts an entirely superfluous anecdote about one of the actors in his commentary for The Wizard of Oz that culminated in a profane quote. I don't recall now which actor, how the story went or what the quote was, but it came in the final half hour, I believe. For nearly any other feature, I might not have even paid any regard to it, but hearing a word like "bastard" (I think that was the one in the quote) while watching that movie really took me by surprise...especially since the anecdote had literally nothing to do with the actual movie!

Tom Weaver's commentary for The Wolf Man included a handful of PG-13 words.

But the granddaddy of 'em all might be the Special Edition (not the Ultimate Edition) of Butch Cassidy and the Sundance Kid where William Goldman cusses up a storm in his interview segments.

another one i thought of, The Bullitt dvd has a feature length documentary on disc 2 about editing which contains strong language, nudity (the famous leg uncrossing scene in basic instinct) and violence