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 DVD audio commentary reveals that the original title of the film was Click. However, the production of an Adam Sandler film of the same name required a change.
In the video store, Celia Imrie notices a stand-up cut-out of her Star Wars: Episode I - The Phantom Menace (1999) co star Ewan McGregor (promotional still from Long Way Round (2004)) and remarks on his attractiveness. McGregor's wife, Eve Mavrakis, was the production designer for "Imagine Me & You."
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.