The dialogue written for the film version of Lost in Yonkers progresses differently than the play, starting from the opening scene. In the play, Arty and Jay are already in the living room, dreading the meeting with their callous grandmother. In the film adaption, the scene opens with Jay’s inner narration, as he, Arty, and his father (Eddie) drive to Grandma’s apartment above Kurnitz Kandy Store. Jay’s inner monologue contextually directs the dialogue for the story, since the play version would not require an opening explanation.

Simon uses colloquial dialogue throughout the script to keep the story moving, but a primary difference between the film and the play is the use of pauses. The play’s dialogue between the characters moves quicker because they don’t have to occupy as much space; in the film, the characters have a filming location to move through, along with scene transitions and background music. This creates a slower pace leading up to the climatic dialogue at the end of scene 1, when Grandma refuses Eddie's request, and Aunt Bella proceeds to lucidly stand her ground, insisting that Arty and Jay stay with them.

After the opening scene of the movie, the film's dialogue closely matches the playscript's dialogue. The pacing of the film's dialogue is simply slower between Jay and Arty due to the screenplay style rather than a script for a live audience.