The film was originally set to shoot in spring of 2008, but was delayed due to Heath Ledger's death. The producers and director delayed the film out of respect for Michelle Williams, Ledger's ex-girlfriend and mother of his daughter Matilda, rather than going ahead and shooting the film with another actress in Michelle's role.
The MPAA originally rated the movie NC-17, but after public allegations of using a double-standard to rate portrayals of sex on-screen, the organization agreed to hear an appeal. Upon review, the MPAA unanimously agreed that the film should receive an R rating. Had the appeal not been granted, it's possible this would have been the first NC-17-rated film to get an Academy Award nomination since Henry & June, and the first for acting.
The scenes in the 'past' when Dean and Cindy are falling in love were shot first, in three weeks. After this Ryan Gosling and Michelle Williams spent a month together in a rented house to age themselves in preparation for the 'present' scenes. They spent a lot of their time grocery shopping, cooking dinner and learning to pick fights with each other.
Michelle Williams was first attracted to starring in Blue Valentine because she liked the script. Just before shooting began, director Derek Cianfrance told Williams that he was no longer interested in sticking to the script, and that he wanted Williams and co-star Ryan Gosling to improvise their scenes. This unnerved Williams, but Gosling said he did not mind improvising as he had trouble remembering his lines.
Steinway Moving and Storage were selected to participate to be in the film. Ryan Gosling was actually working and conversing with the company's employees. The owner, James "Jamie" Benatti, played himself.
Derek Cianfrance spent 12 years making the movie. During that process, Cianfrance said that he wrote about 67 drafts, mostly each draft containing content added / modified based on on-set improvisations, inspirational encounters etc., while he worked on several documentaries to secure more funding for the movie.
When it came to casting Dean and Cindy's daughter, Derek Cianfrance asked Michelle Williams whether she could use her daughter Matilda to play the role. Williams considered briefly, but after noticing that the child's interest lies beyond acting (she was quoted that Matilda's main hobby was horse riding), Williams declined.
When filming the argument scenes, Derek Cianfrance gave instructions to Michelle Williams and Ryan Gosling individually without the knowledge of the other in order to create more tension between Dean and Cindy. For Williams, Cianfrance would instruct her to try to leave the room, use any way to break out of the argument with Gosling etc. For Gosling, Cianfrance would tell him to use any means to persuade, get Williams attention, etc. Gosling has stated it was a new and interesting process as it became a tug game on set.
Derek Cianfrance had set the film in numerous places during script rewrites and redrafts including Florida and Hawaii. He finally decided on New York when Michelle Williams became involved so that she could go home and see her daughter.
According to Derek Cianfrance, after shooting the first part of the love story, there were serious discussions about not doing the second one, retitling the movie simply "Valentine", and make it a depiction of falling in love.
The trivia items below may give away important plot points.
Cindy tells Dean that he has potential in life because of his artistic talents. The argument about potentiality was based on a talk between ''Derek Cianfrance'' and his wife about getting the film made for many years.
Some have speculated that Dean and Cindy have ended their marriage. One of the photos during the end credits shows Dean and Cindy running backwards holding a sign with "Is This You?" on it, hinting the upcoming dissolution of their marriage.