J.K. Simmons said that he was so impressed with the script that he would have been happy just to play the teacher who has no spoken dialogue - anything to appear in the film.
It was challenging to show all four seasons within a 30-day filming schedule. Solutions included digitally darkening spring cherry blossoms to look like summer flowers and having crew members off camera throw falling silk leaves for autumn. There was a fluke snowstorm (unusual for March in Vancouver) and three different shots were coordinated that day before the snow could melt. Since fake snow can be expensive to put in a shot, this saved the film considerable money for the winter scenes.
After box-office success and gaining a large following, Jason Reitman was asked by executives on the possibility of doing a sequel, to which he stated "What could it possibly be, Juno gets pregnant again?!" and concluded the story of Juno was complete.
Jennifer Garner dropped her A-list salary to a percentage point agreement for Juno when it was expected to be a small, low-grossing indie film, but the decision paid off when Juno became a breakout smash at the box office - giving Garner her best payday yet.