In typical Jack Webb fashion, principal photography was finished in only 12 of the scheduled 18 days.
The daily newspaper in the film was loosely based on the real-life newspaper Los Angeles Herald-Examiner. According to an article in the December 1959 edition of American Cinematrographer, one interior set was built measuring 200 by 60 feet that replicated that newspaper's newsroom.
"-30-" is used to signify "the end"; it originates from several code tables for telegraph operators. It is traditional in the journalism field and is still used to indicate the end of transmitted news stories and press releases and can frequently be found in formal corporate documents posted on websites and delivered electronically or via print.
According to the American Film Institute Catalog entry for this film, production charts from The Hollywood Reporter state this film was made at Republic Studios (now CBS Studio Center in Studio City, Los Angeles). However, another source referenced in that entry states it was made at Warner Bros.
The calendar on the wall in the first scene sets this film in November 1959.