An Opera singer named Giovanni Jones gets annoyed at an as-yet-unaware Bugs for playing his banjo, harp and tuba and therefore distracting him from his singing practice. However, rather than politely ask Bugs to stop playing during his rehearsals, he uses the instruments as weapons to clobber Bugs. Bugs is initially tolerant of the singer's apparent rudeness, taking the first two attacks in stride; but after a third instance of such brutality, where his ears are tied to a tree branch and pulled like a slingshot, Bugs faces the audience and declares his time-honored, Groucho Marx-inspired warning: "Of course you know, this means war!"
Bugs exacts his revenge against Jones first by hammering the roof of the "acoustically perfect" concert hall (presumably the Hollywood Bowl, due to its shape) to disrupt the singer's vocals, then by spraying his throat with "alum" which shrinks his head as well his voice. Next, Bugs dresses up as an adoring teenage female fan and asks Jones for an autograph, only the pen is a stick of dynamite.
Finally, for the coup de grâce, Bugs poses as the highly respected "Leopold" (Stokoswki) to take over the conducting duties. Bugs conducts Jones through a virtuoso (albeit unorthodox) performance before administering the final blow: holding a singular note until Jones can hardly endure the strain (at one point, Bugs leaves his glove hovering in the air and steps outside to order a pair of ear muffs). Giovanni's face turns different colors as his tuxedo unravels under the pressure (collar detaches, vestee bursts off, dickey rolls into face, suspenders give and slacks fall around ankles). Bugs returns to his glove to find Jones on the floor banging his fists in what's left of his torn apart tuxedo and flowered boxer shorts. Eventually the concert roof comes crumbling down on top of the unfortunate singer. When Jones climbs out of the rubble, he takes a bow in shreds that were once a tuxedo. His face is beaten in and bruised purple and blue. Bugs again cues Jones to sing the same note so that a boulder, precariously balanced on a steel girder, falls and crushes the singer's head.
To add insult to injury, Bugs removes his wig and closes out the performance by strumming the old vaudeville-era four-note tune, "Good Eve-ning Frieeeeends", on a banjo as the cartoon ends.
The short's musical score includes original music by Carl Stalling, but a significant proportion of the score is pre-existing music, including several operatic pieces. The following pieces are used in the film:
Gioacchino Rossini - "Largo al factotum" from The Barber of Seville - Opening titles, Giovanni Jones' rehearsal scenes and second piece at concert
Arthur Schwartz - "A Rainy Night in Rio" - played by Bugs on a banjo
Barney Fagan - "My Gal is a High Born Lady" - played by Bugs on a harp (melody only). The original subject and lyrics depicting racism in this popular 1896 song were not used. Instead, Bugs' song lyrics were re-written as an enjoyable testament to his gal's dancing prowess. The author of the re-written lyrics is unverified, but possibilites include Carl Stalling or Michael Maltese.
Herman Hupfeld - "When Yuba Plays the Rumba on the Tuba" - played by Bugs on a tuba
Gaetano Donizetti - "Chi Mi Frena In Tal Momento" from Lucia di Lammermoor - first piece at Giovanni Jones' concert. (This makes no sense, since the piece in question is a sextet, with a tenor (Edgardo) and a baritone(Enrico) making the joint first entry and four other character to join the sextet shortly thereafter; no one else but Giovanni Jones is on stage, so how he's going to sing a sextet by himself is unclear).
Richard Wagner - Prelude, 2nd theme from Act III of Lohengrin - autograph scene
Franz von Suppé - Overture from Die schöne Galathee - Bugs enters in 'Leopold' disguise
Giovanni Jones' singing voice remained uncredited and unknown for many years. It was since revealed to have been provided by opera singer Nicolai Shutorov. This is noted in the commentary voice-over provided on the DVD.
Also noted on the DVD commentary is Bugs Bunny's conducting performance as "Leopold", as a send-up of conductor Leopold Stokowski's energetic style, including his shunning the baton. As Bugs enters the concert hall wearing a Stokowski-like hairpiece, the orchestra members begin whispering among themselves, "Leopold! Leopold!". The DVD commentator also notes that Stokowski conducted many performances at the Hollywood Bowl, where the second half of this film is set.
An edited version of Long-Haired Hare was included in The Bugs Bunny/Road Runner Movie (1979).
Giovanni Jones can be seen in Space Jam during the basketball game.
When the short aired on ABC, the entire "bobby-soxer" sequence was omitted.
On CBS (whose programming people at the time despised the cartoon due to how violent it was), the "bobby soxer" scene was also deleted, as well as the scenes in which Jones attacked Bugs after interrupting his singing (breaking apart his banjo and smashing the remnants of it over Bugs' head, slamming the harp on Bugs' neck, and pulling Bugs out of the tuba, tying his ears to a tree branch and pulling his body back so he snaps back and his head hits the branch).