On the same day as the funeral scene was filmed, President John F. Kennedy (a personal friend of Frank Sinatra's) was assassinated.
After the assassination of President John F. Kennedy, Frank Sinatra regretted for the rest of his life leaving in the line "You come over like George Washington I'll send you back like Abe Lincoln."
Although his name doesn't appear in the credits, the distinctive voice of the "radio announcer" heard emanating from the speaker outside the radio supply store twice during the movie belongs to Paul Frees.
The two lesser-known Rat Packers, Joey Bishop and Peter Lawford, don't appear in this film. They were essentially "replaced" by Peter Falk and Bing Crosby, respectively.