(1) Pardon my ignorance, Bardford, but what's wrong with bodhrans on the Titanic?

(2) Here's Mark Twain on authenticity, from the preface to "The Adventures of Huckleberry Finn:"

"IN this book a number of dialects are used, to wit: the Missouri negro dialect; the extremest form of the backwoods Southwestern dialect; the ordinary 'Pike County' dialect; and four modified varieties of this last. The shadings have not been done in a haphazard fashion, or by guesswork; but painstakingly, and with the trustworthy guidance and support of personal familiarity with these several forms of speech.

"I make this explanation for the reason that without it many readers would suppose that all these characters were trying to talk alike and not succeeding."

(3) A friend of mine who plays piano is annoyed when people try to talk to her while she's playing. She calls it the "Dooley Wilson syndrome." Apparently Dooley Wilson, as Sam, really did play the piano in "Casablanca," and he really could play and talk at the same time. This has led countless non-musicians to assume that all pianists can do so.

(4) Here is the IMDb page of goofs in "Casablanca." It has some interesting comments on the "letters of transit."