The dummy front pages both have the same photo of the man to be executed, showing him behind bars. That is, except for the close-up shot of the page just before the editor jumps up and decides to go with his hunch - that shot shows a full-faced photo with a manic expression, and no bars.
When Steve throws his typewriter and breaks the glass in his office door, it breaks in one pattern. In the next shot as Laurie approaches the door, the glass is broken in a different pattern.
When Laurie pushes Steve into a chair in his office, he lands with one leg over an arm of the chair. But, in the next shot, both of his legs are in the chair.
The list at the cemetery shows that Crowder was interred in the third week of October. Steve got in trouble near the same day, got demoted and wrote the advice column for ten days before starting his investigation of the suspicious lonely hearts club, which was finished within a couple of days. Thus, when they get to the cemetery, the date has to be somewhere in the first week of November. However, the list of interments at the cemetery includes seven people who were interred after mid-November.
Crowder died a couple of days after visiting the newspaper offices in which a May 1942 calendar was on the wall. However, the date Crowder was interred was shown as being in October 1942.
There is a grammatical error in the sign outside the Lonely Hearts Club. The sign reads "If You're Lonely, Your Welcome." Of course, the sign should read "If You're Lonely, You're Welcome."