AS production began early this year on his new comedy, "Zack and Miri Make a Porno," Kevin Smith was still seeking an actor for a supporting part. So he asked for suggestions from his leading man, Seth Rogen, who was in "The 40-Year-Old Virgin" and "Knocked Up," two comedies written and directed by Judd Apatow, and one of the writers of "Superbad," which Mr. Apatow produced. Mr. Rogen recommended Danny McBride, who appeared with him in "Pineapple Express," another Apatow production.
Then Mr. Smith surveyed his "Zack and Miri" cast. Mr. Rogen's co-star is Elizabeth Banks, who was featured in "The 40-Year-Old Virgin." Craig Robinson, who appeared in "Knocked Up" and "Pineapple Express," also has a role. So does Jerry Bednob, another alumnus of "The 40-Year-Old Virgin." Ultimately, Mr. Smith declined Mr. Rogen's suggestion.
As Mr. Smith recalled in an interview: "I had to actually stop him and go, 'Shouldn't you ask your boss or something? There's a lot of people from his movies.' "
Mr. Smith's predicament is just one part of a larger problem facing many filmmakers in the field of R-rated comedy: It is nearly impossible for them to make their pot-smoking, breast-baring (but heartfelt!) movies without in some way encroaching on the raunchy (yet tender!) turf that Mr. Apatow already owns.