This was the first film Rita Hayworth made for Columbia Pictures Corporation.
It's working title was "Fer-de-lance," the title of the source novel,
On finishing his dinner, Wolfe says, "Fate cannot harm me, I have dined today." This is the last line of a poem by the eighteenth-century clergyman and wit Sydney Smith.
This movie appears to be the first one ever to include a game of Monopoly (first marketed in 1935) included in the plot.
Nero Wolfe is incensed that Archie has spent 20 cents on a phone call, and says "You spendthrift! Get to work!". That 20 cents would be equivalent to just over $4 in 2022 - if payphones were still in use.