After the title credits, the movie opens with Stanley (Don Johnson) watching the construction of the World Trade Center twin towers at a very early stage.
Warhol veteran Joe Dallesandro was originally cast in the role of Danny. Dallesandro was fired when he would consistently arrive on the set late and cause trouble with the cast and crew. Ironically, Andy Warhol himself later referred to the film as "the quintessential, most truthful studio-made film about the '60s counterculture".
Don Johnson's film debut.
The New York Times reported in October 1969 that 'Sweetheart' had been cast with Ultra Violet, Candy Darling, Gerard Malanga, and was to feature Andy Warhol in his very first Hollywood film role, that of a "freaked-out psychiatrist." This obviously didn't happen.
The film was chosen to be screened at the New York Film Festival in October of 1971.