The sequence toward the end, where the cast is at the side of the building and Benny battles the Paradise Coffee moving ad, was scored by Warners composer Carl W. Stalling, using his trademark violin string up-slide twang sound and his paraphrasing of the work of Raymond Scott. Stalling was used to give the scene a Warner Brothers cartoon feel.
The notion that coffee makes you sleep was topical. It appears not only here (in the Paradise Coffee commercial), but also in the Maxford House Coffee slogan contest in Christmas in July (1940) (by a different studio).
Aside from guest appearances in It's in the Bag (1945) and A Guide for the Married Man (1967), this was Jack Benny's final feature film. He frequently joked about The Horn Blows at Midnight on his radio and TV shows, saying that it was so awful that it ended his career.
At the time this was made, Jack Benny was the star of one of the most popular shows on radio, regularly ranked among America's top ten broadcasts. But Benny was never able to parlay that popularity into box office appeal, and when Warners lost a fortune backing this film, Benny was relegated to only making cameo appearances in movies for the rest of his career. Benny did benefit from being in this film, though, by bragging for decades afterward that he had starred in one of the biggest bombs in Hollywood history.