Alternate versions

The director's cut contains approximately 5 minutes of new footage, including:

• Melvin Belli (Brian Cox) talks about his Safari trip (when the Zodiac letter came to his house)
• Toschi (Mark Ruffalo) introduces himself to the Riverside Police Chief
• A new scene between Graysmith (Jake Gyllenhaal) and Avery (Robert Downey Jr.)
• A three-way conversation laying Leigh as a suspect to get a search warrant
• Extended audio montage (over a black screen)
• Plus extra bits of dialogue

The end credits of the Director's Cut has a more detailed final cast listing. It properly credits many of the actors who were inexplicably left uncredited in the theatrical cut. However, Ione Skye's cameo as Kathleen Johns remains uncredited even in the Director's Cut.