Inside a theater in Mexico, one of the men, the dapper and refined French tenor Armand Dupres sings an operatic aria.

While learning facts about his life (e.g. he was born on a boat to Mexico), the call girl tries to seduce him but he refuses, saying that sex has gotten him into trouble in the past.

Dupres and Bernini express disgust that Palacios got them to record duets with pop singers, dress as mariachis, and promote Pizza Hut and the World Cup, when what they do is art.

Telling the son that he has conducted modern music like his, he convinces them to perform the composition at a party on the eve of Dupres' wedding, claiming to his former partners that these were his three young discoveries.

After the party, Bernini unsuccessfully tries to kill himself, despairing over his thirty-year rivalry with Palacios, while Dupres' fiancée realizes she is actually in love with his son.

The next day at the wedding Palacios, after bragging about his acting abilities in Otello, pretends to have a heart attack in order to distract the paparazzi while his daughter and Dupres' son run away together.

Around a decade before Off Key was filmed, the most famous operatic tenors in the world, Luciano Pavarotti, Plácido Domingo, and José Carreras, appeared together in their first concert, the recording of which became the best-selling classical album of all time.

[5] When asked whether the production encountered any problems from the real Three Tenors, the film's producer, Andrés Vicente Gómez, told the press that Carreras' lawyer had contacted them at the start of the project.

[6] When asked why the character loosely inspired by Carreras was French instead of a Catalan from Spain, the producer joked that the change in nationality was "something to spare us from a trial.

Like the director Gómez Pereira, Danny Aiello (Bernini in the film) insisted: "The parallelisms with the Three Tenors are inevitable, but our intention is not to interpret Pavarotti, Carreras, or Domingo...Any resemblance to reality is pure coincidence.

[8] One of the movie's screenwriters explained that he viewed the character of Palacios as someone who is extroverted and commercial-minded, while Dupres is more interior oriented and Bernini is quirky and superstitious.

As the film starts, Dupres sings the "Flower Song" ("La fleur que tu m'avais jetée") from Bizet's opera, Carmen.

In the aria, the character Don José tries to convince the wild Gypsy Carmen (also the name of Palacios' daughter in the movie) of the depth of his love for her.

José Carreras recorded the complete role under the renowned conductor Herbert von Karajan in 1983, while Plácido Domingo starred in a movie version of the opera in 1984.

Later at the wedding party, the tenors sing the "Brindisi" ("Libiamo ne' lieti calici") from Verdi's La Traviata with Palacios' young discoveries.

[12] The aria that Bernini sings near the end of the film, "Nessun Dorma" from Puccini's Turandot, became Luciano Pavarotti's best-known song and reached the second spot on the British charts in 1990.

The mariachi song, "Guadalajara", that brings the downfall of the tenors in the film, has been a lasting classic of the genre, sung by performers as diverse as Vicente Fernandez and Elvis Presley.

The movie also features an original piece written by Bernardo Bonezzi, which acts as Dupres' son's composition during the party scene.

The reviewer for Variety was unimpressed by the movie's screwball comedy script and likened it to a series of underwhelming English-language films made by Spanish moviemakers.

"Despite thesps' histrionics," the reviewer wrote, "characters rarely escape stereotype, whether it be Mantegna's frenzied Spanish gesturing—though his accent sounds more Italian—Hamilton sleepwalking through Dupres, or [the call girl] Violeta's desire to get rich quick.