One That Got Away
Not complaining, merely throwing it out there for discussion (if it's already been dealt with elsewhere, my apologies).
The Hayes Code (whereby crime does not pay; criminals must be punished) apparently wasn't too strictly enforced regarding comedies.
Although he wasn't the actual killer of the unseen Mr. Spinazzo(?), and also may not have witnessed it, Dr. Einstein (Peter Lorre), was an accomplice in the attempt to cover up that crime by helping Jonathan hide the body. And later he's a participant (albeit somewhat reluctantly) in the near-demise of the hapless Mortimer.
I know they were just following the play, but any change wouldn't have been the first time changes occur during the transfer of a play into film. Of course, all of us fans certainly didn't mind in this case (since we like Lorre, despite his creepiness), but I don't recall any other of these old 1930s-1940s flicks in which even an accomplice is allowed to get away scot-free.
Oh yeah, it's a very funny film, but it would have been much better with James Stewart and Boris Karloff.
And the 1969 telefilm (available on Youtube) with Bob Crane, Fred Gwynne, and Jack Gilford, ain't bad either.