Stupidity: During the final phases of the Turnabout Sisters case, trying to press Redd about him not being solely guilty of wiretapping will cause Edgeworth to state that "unidentified fingerprints several days old were found in the Fey and Co. Law Offices" and they'd "obviously" belong to Redd. That's an unnecessarily ridiculous non sequitur; being an office with several clients, it'd be astonishing if there were no "unidentified prints" at all.
Character mistake: When the first case's true murderer is KO'd by Phoenix's amazing attorney skills, he is carried away from the courtroom. The Judge then asks to the prosecutor, "Mr Payne, your client?" He should have obviously asked, "Mr Payne, your witness?" And that's exactly what he asks in the Trilogy remake, that fixes this mistake.