Animal Crackers follows a family, led by Blunt and Krasinski's Zoe and Owen Huntington who inherit a ramshackle circus. When they partake of the titular biscuits, they find themselves transformed into animals and other characters.
"When Emily and John came in and performed their first scenes of the movie together... It was magic," Sava, who also co-wrote the script with Dean Lorey, tells Screen International. "I can think of no other way of describing what they brought to the film. We had to literally go back and re-storyboard the sequences because they took us to places we never dreamed. Owen and Zoe came to life when Emily and John spoke."
Danny DeVito (Matilda), Harvey Fierstein (Independence Day) and Patrick Warburton (Rules Of Engagement) will will also be lending their vocal talent, while voice artists Tara Strong (Princess Mononoke), Gilbert Gottfried (Aladdin), Arnold Taylor (Star Wars: The Clone Wars) and newcomer Lydia Taylor make up the rest of the cast for the film, which should be ready for cinemas next year.