Shirley Jones learned she was pregnant with her son Patrick once the filming of had begun. She met with director Morton DaCosta over lunch to inform him of the situation. Her concern was that she would begin "showing" during its filming. He assured her that they could work through it with costumes and also by filming her from the waist up, if necessary. He did have one request, that she tell no one about it. Robert Preston did figure it out before filming had concluded, when Shirley's character, Marion, and his character, Professor Hill, kissed for the first time in the romantic footbridge scene. He leaned in for the kiss and jumped back, asking her, "What was that?" to which she replied, "That is Patrick Cassidy! Say, 'Hello!' " Years later, her son Patrick had the opportunity to meet Preston. He walked up and introduced himself saying, "Hello. I'm Patrick Cassidy." Preston replied, "Yes, I know. We've already met."
In the original Broadway cast recording, there was a verse in the song "Rock Island" that goes, "Why it's the Uneeda biscuit made the trouble, Uneeda, Uneeda, put the crackers in a package, in a package, the Uneeda biscuit in an airtight sanitary package, made the cracker barrel obsolete!". This verse was omitted from the film version of the song. The Uneeda Biscuit was a revolutionary cracker that promised to be airier, flakier, and crisper than most other crackers. The cracker was kept fresh in a brand new concept of resealable packaging. Uneeda Biscuit was developed by the National Biscuit Company, nowadays known as Nabisco.
In an episode of the TV series Happy Days (1974), Howard and Marion Cunningham are coming out of a movie theater; they pause in the lobby and look at the poster for "The Music Man". Marion comments how much the little boy in the movie (Winthrop) "looks so much like Richie did when he was little". Both Winthrop and Richie were played by Ron Howard.
The original Broadway production of "The Music Man" opened at the Majestic Theater on December 19, 1957, ran for 1375 performances and won the 1958 Tony Award for Best Musical. Robert Preston, Pert Kelton, The Buffalo Bills, Peggy Mondo, Adnia Rice and Paul Ford reprise their roles in the movie. Ford was a replacement during the original run. Preston won the 1958 Tony Award for Best Actor in a Musical.
In the diner, Harold Hill attempts to remember a William Shakespeare quote: "Cowards die a thousand deaths, the brave man... only 500," to which Marian replies "something like that." The quote he looks for is from "Julius Caesar", Act 2, Scene 2, when Gaio Giulio Cesare says, "Cowards die many times before their deaths, the valiant never taste of death but once."
During the "Lida Rose"/"Will I Ever Tell You" duet both Mrs. Paroo (Pert Kelton) and the lead singer of The Buffalo Bills (Vern Reed) are in rocking chairs. They are synchronized throughout much of the song, starting, stopping and rocking together. This is only visible in the wide screen version.
The inscription on the statue of Henry Madison (Madison Picnic Park, Madison Library, etc.) in front of which Harold Hill sings "Trouble" is inscribed as follows: "Clean your finger before you point at my spots."
Zaneeta has a meeting of the Epworth League. This organization was formed by combining young people's organizations of the Methodist Episcopal church, with its purpose being to promote intelligent and vital piety among the young people of the church.
When Eulalie Mackechnie Shinn (Hermione Gingold) is performing in the "spectacle" with her schoolchildren, she says "Now count to twenty in the Indian tongue..." and proceeds to count in what seem to be nonsense words ("Een! Teen! Tether mether fip!..."). It's actually a variant of traditional British sheep-counting.
For the final "76 Trombones" marching band number, the "Courthouse Square" set at Universal Studios was used as the location set for River City. It has been featured in many films, most notably as Maycomb, Alabama in To Kill a Mockingbird (1962), and as Hill Valley, California in Back to the Future (1985). In 2008, the "Courthouse Square" set burned down, but it has since been rebuilt.
Despite Robert Preston's Tony-award winning performance in the Broadway production, Warner Bros. executives wanted a bankable star in the lead role of Professor Harold Hill for the movie. Frank Sinatra was offered the part, but turned it down. Cary Grant was also approached, but told the Warner Bros. executives, "Not only will I not star in it, if Robert Preston doesn't star in it, I will not see it." Preston finally got the part, and the movie was a big success, despite Warner Bros' misgivings.
In the "Wells Fargo" song, a River City citizen sings, "Montgomery Ward sent me a bathtub and a crosscut saw." Montgomery Ward is the name of the world's first mail order business. Founded in 1872 by Aaron Montgomery Ward, it went out of business in 2001. Also in the song, The Buffalo Bills sing, "The D.A.R. has sent a cannon for the courthouse square." The D.A.R. is the "Daughters of the American Revolution", a non-profit, non-political volunteer women's service organization. Made up of descendants of soldiers in the American Revolution, they are dedicated to promoting patriotism and preserving American history. However, the organization is probably most noted for refusing to let the great African-American contralto Marian Anderson perform in 1939 at the D.A.R.'s Constitution Hall because she was black.
The location set for River City's town square, where Harold Hill sings "You Got Trouble," was Warner Bros.' famous "Midwest Street,", featured in films like East of Eden (1955), Bonnie and Clyde (1967), and The Muppets (2011), and in TV shows like The Dukes of Hazzard (1979) and Sisters (1991). The storefront used for River City's Candy Kitchen is the same front used for Mr. Doose's old-time candy store in Gilmore Girls (2000) television series 40 years later.
Paul Ford, who plays Mayor Shinn in this film, also plays Horace Vandergelder in The Matchmaker (1958). David Burns, the actor who played Mayor Shinn in the original Broadway production of "The Music Man", played Vandergelder in the original Broadway production of "Hello, Dolly!" (which is adapted from "The Matchmaker").
During production, President John F. Kennedy asked for creative contributions to the Presidential Council on Physical Fitness. In response, Meredith Willson wrote and Robert Preston and the band performed the song "Chicken Fat".
When Harold Hill and Marion Paroo are standing on the footbridge, Marcellus Wallace appears in the nearby bushes, trying to get Harold's attention. Harold tells Marion, "Excuse me. I've been expecting a telegram from Rudy Friml. This may be it." Rudolf Friml was a Czech-born composer of operettas, whose best-known works were The Firefly (1937), _Rose Marie (1935)_, and _The Vagabond King (1929)_.