At 82 years of age, Christopher Plummer won an Academy Award for Best Supporting Actor for this film and became the oldest person to ever win an Oscar for acting.
Ewan McGregor was not a dog owner before he made the film. During the course of the shoot, he decided that he absolutely had to get a dog and is now the proud owner of a poodle named Sid.
The film is partly autobiographical, in that many of the events that happen to Hal and Oliver are based on Mike Mills' own father having begun a gay relationship after Mike's mother died.
Mike Mills did not originally intend for Anna to be French, but after asking Mélanie Laurent if she could completely lose her accent and finding out she could not, he changed the character for her.
Mike Mills has a background in graphic design, so he trained Ewan McGregor in some of the rudiments of it for his characterization.