The premise of the movie is invalid because only women could sue for breach of promise to marry, not men.
During the climactic courtroom scene when Hepburn appears in a hallucination to Olivier as a Shakespearean actress she is garbed in feminine frills as she gives Portia's famous speech-- also in a courtroom-- which is wrong because at this point in "The Merchant of Venice," Portia would be disguised as a man.