Although it was announced in 2014 that U2's Bono and The Edge were working with John Carney on this film, the collaboration did not come to fruition, except some back and forth in the development stage, due to scheduling conflicts.
While there are similarities to The Commitments (1991) (including the casting of Maria Doyle Kennedy), director John Carney has explicitly stated in an interview with The Verge that no homage to that film was intended. He also debunked the notion that the use of rabbits in Sing Street is a reference to the character Jimmy Rabbitte in the earlier film. Rather, it was a characteristic of the real-life "Eamon" that he knew as a teenager.
The trivia items below may give away important plot points.
John Carney on the ending: "Well, I don't see it just as a happy romantic ending. I think that's the tone of the piece, but I think it's more like... they're setting off together, that's true, but I wouldn't say that's some huge relationship that's going to last forever. They're kids. I sort of hope the scene at the end would look a little like a fantasy sequence. You're supposed to wonder where the reality ends and the pop video begins. But people are actually taking it very seriously, and people are presuming it's fully real, which is interesting. That wasn't the intention."
When Conor first goes to Eamon's home at night to create a song with him, he has three LPs with him. Conor and Eamon play tracks from two of them ("Steppin' Out" by Joe Jackson, and "A Town Called Malice" by The Jam), but not from the third LP. That third LP, which can be partially seen on the room's floor: "Regatta De Blanc", by The Police.
During Conor's discussion with Brother Baxter about his use of makeup, Baxter claims that, if Conor is Mozart, that would make Baxter Salieri. Antonio Salieri was an Italian-born composer, contemporary of Mozart, and generally thought to have been one of his biggest rivals and competitors, using his position in the court of the Holy Roman Emperor to secure prominent jobs and staging for his work, while blocking the development of Mozart's career.
The film contains several references to the film Back To The Future. In the Senior Prom section at the end of the film, it contains an identical shot to Back to The Future when a scoop of punch is poured into a glass.