Breaking with their usual pattern, neither Harpo's harp nor Chico's piano is used in the film, although Harpo briefly pretends to play harp on the strings of a piano.
The musical introduction to Groucho's character is similar to those in Animal Crackers and Horse Feathers, but it did not become closely associated with him as did "Hooray for Captain Spaulding" from Animal Crackers.
Zeppo, playing according to James Agee "a peerlessly cheesy improvement on the traditional straight man",[19] sings with the group, including soloing the first few lines of the first song, "When the Clock on the Wall Strikes 10". He also sings with the others in "Freedonia's Going to War", filling out the four-cornered symmetry as the Brothers sing and dance in pairs during the number.[7]
Original songs by Kalmar and Ruby
The "Freedonia National Anthem" is used frequently throughout the film, both as vocal and instrumental; the entire song seems to consist of "Hail, Hail, Freedonia, land of the brave and free", contrasting with the final line of The Star-Spangled Banner. The "Sylvania theme", which sounds vaguely like "Rule, Britannia!", is also used several times. "When The Clock On The Wall Strikes 10", the first musical number in the film, is part of the same scene as "Just Wait 'Til I Get Through With It",[6] Groucho's song about the laws of his administration. "This Country's Going To War"[20] is the final musical ensemble in the film. Technically it is the only musical number in the Marx Brothers' films to feature all four of the brothers. However, in Monkey Business, Chico briefly bangs on the piano while the other three play saxophones while eluding their pursuers on an ocean liner.
The introductory scene, showing ducks swimming in a kettle and quacking merrily, is scored with an instrumental medley of the aforementioned songs, and it is also the only scene in the film that has to do with ducks and soup.
Non-original music
- Military Polonaise (Chopin) – played over newspaper headline of Firefly's appointment as president of Freedonia
- "Sailor's Hornpipe"; "Dixie" – short segments embedded in "These Are the Laws of My Administration"
- "Who's Afraid of the Big Bad Wolf" – music box, accompanied by Harpo on (simulated) harp, briefly; a few minutes later, in another scene, Groucho says "I'll huff and I'll puff and I'll blow your door in" after he is locked in a closet. Walt Disney filed a lawsuit against Paramount Pictures, for using the song without permission, resulting in Disney winning the financial damages in a settlement.
- "Stars and Stripes Forever" (Sousa) – on radio, turned on (loudly) by Harpo, who mistakes it for a safe
- "American Patrol" (Frank W. Meacham) – three of the Brothers playing soldiers' helmets like a xylophone as they march by, while Harpo clips off the decorative tassels (part of a running gag in the film)
- "All God's Chillun Got Guns" (parody of "All God's Chillun Got Wings"); "Oh Freedonia" (parody of "Oh! Susanna"); "Turkey in the Straw" (instrumental) – embedded in "Freedonia's Going to War"
- Light Cavalry Overture (Franz von Suppé) – Harpo galloping on horseback a la Paul Revere
- "Ain't She Sweet" (Milton Ager/Jack Yellen) – Harpo watching girl in window
- "Goodnight, Sweetheart" (Ray Noble) – Harpo and same girl (Edgar Kennedy's character's wife)
- Generic cavalry charge – Harpo with horn, in bathtub with Edgar Kennedy
- "One Hour With You" (Oscar Straus/Richard A. Whiting) – Harpo with another girl and his horse — segué into a bit of "The Old Gray Mare"
- "El manisero" (Moisés Simons) – half-sung, half-muttered by Groucho to himself at various points
