At about the 44-minute mark, Perry fires a gun in the courtroom as a test. Before the test, the prosecutor had on a dark suit. After the gunshot, the prosecutor can be seen in a light-colored suit. The trial resumes, and the prosecutor is again in a dark suit. Besides this, the entire spectator section changes after the test and back again as the trial resumes. The trial resumes the next day. The prosecutor is in his light suit and the spectators are the same as after the gunshot test the day before.
The private investigator Morgan would not allow Drake to take his carbon copy of his report out of his office. Once it leaves the office can no longer prove what the original copy said. And he would not leave himself exposed by letting Drake leave with it. Drake could say he never got it.
There is no such place as Bardo, California. This is not a goof. This was intentional. The series often used fake place names in California, such as Logan City that was used in several earlier episodes.
The report from private eye Morgan was typed in a manner that would allow the word "not" to be inserted at the end of the line in order to confuse matters for the plot. The second line (absent the word "not" which was added later by Salty) would have too much white space after the word "definitely." There is enough white space for at least the word "brother" to have been included at the end of the line. Ordinarily, someone -- especially a private eye typing a report for a client -- would type to the end of the line so the sentence could not be altered.
In the outside shot of the courthouse before the trial started, the cars are all vintage 1930s and 1940s, even though the story takes place in 1959. It's obviously footage from a much earlier film.
In the epilogue, Perry suddenly leaves the conversation with Paul and Della to buy a pack of cigarettes from a machine. Perry did not pull the handle to register a purchase. The pack was already in the tray.
The manager of the motel was never sworn in, so the registration cards from the motel were not properly placed into evidence. He should have been put on the witness stand and verified under oath that the registration cards were genuine.
The view outside the sliding door at Clark's house is obviously a back drop, for a sound stage.
The sign for Bardo is on the wrong side of the road.
Someone altered the report sent to Salty Sims by the private investigator. Perry refutes Sims's claim that he never touched the typewriter that was used, by showing Salty and the Judge the letter Sims himself typed, signed, and sent to the investigator before hiring him. But the only 'n' in that letter does not show the heavy stress characteristic of 'n' on that typewriter.