Pacino shot the first scene wearing sunglasses, but he asked the director to re-shoot it after watching the dailies, as he felt that Sonny "wanted to get caught". He also shaved off a moustache he grew for the role after the replay. Lumet allowed the cast to ad-lib lines with the condition that they did not deviate greatly from the script by Pierson. The production team had recorded improvisations during the rehearsals that were added to the script. Lumet wanted the dialog to "feel natural", and he encouraged the actors to wear their own clothes and to not use makeup.