All corrections
1
Claim
Pentangeli betrays the Corleones and collaborates with the police, preparing to testify against Michael in court, but is then scared when his own brother shows up in the courtroom, disapproving of the betrayal.
Correction

In The Godfather Part II, Pentangeli is cooperating with the FBI and is set to testify at a U.S. Senate hearing, not in a court proceeding with the police.

Full reasoning

This sentence misstates both the institution Pentangeli is cooperating with and the setting of his testimony. The AFI Catalog summary of The Godfather Part II says Pentangeli is "cooperating with the FBI" and that he is "set to testify" at a Senate hearing. A transcript of the scene likewise labels it "Frankie Pentangeli Testifies Before the Senate Committee," and Pentangeli says on the stand, "I live ... in an army barracks with the FBI guys." So the scene is a Senate committee hearing, not a courtroom, and the cooperating federal agency is the FBI rather than "the police."

2 sources
Model: OPENAI_GPT_5 Prompt: v1.16.0