The film was originally conceived and written as a heterosexual love story.
The title comes from the first four words of the song "Happy Together" by The Turtles, also used as the end credits song.
The film takes its title from the song "Happy Together," by The Turtles. Writer and director Ol Parker reveals on the DVD audio commentary that the film was originally titled Click, after the French term for love at first sight, but conflicts with the Adam Sandler film Cambia la tua vita con un click (2006) necessitated the name change.
In the video store, Celia Imrie notices a stand-up cut-out of her Star Wars: Episodio I - La minaccia fantasma (1999) co star Ewan McGregor (promotional still from In moto in giro per il mondo (2004)) and remarks on his attractiveness. McGregor's wife, Eve Mavrakis, was the production designer for Imagine Me & You (2005).
In the audio commentary the director mentions that the hat Rachel (Piper Perabo) is wearing during the soccer game is actually a crew member's. She was cold and tried on different people's hats until she found one she liked.