Several scenes in the jury room have Juror #12 (William Petersen) with a pair of sunglasses on his head, off his head, and back on his head again.
When #8 (Jack Lemon) takes a cough drop and starts talking again, there is a shot of #2 (Ossie Davis) putting the box back in his shirt pocket. A few seconds later, he puts it into his shirt pocket again.
When Juror #3 gets up to demonstrate the stabbing on Juror #8, he opens the blade twice.
After it starts raining, and they take a break, Juror #7 picks up a piece of wadded up paper twice between shots.
Newspapers are seen in the jury room. While prospective jurors are permitted to bring reading material to a courthouse/trial, newspapers are prohibited, as said papers may contain information regarding the case that could give bias to the jurors.
When Jack Lemmon says the hallway is 43 feet 6 inches, you'll notice the diagram shows the hallway as 43 feet. His second reference to the hallway is correct at 43 feet.
In the original 1957 script, the defense attorney is referred to several times as 'he'. In the 1997 script, the defense attorney is again referred to as 'he', but, in the opening scene of the 1997 version, the defense attorney who is sitting next to the defendant is a woman. The trial itself isn't shown, so it's possible they may have been talking about an additional male member of the defense that we didn't see in the film.
Juror #10 refers to Hispanics as wetbacks. Wetback is the offensive term given to Mexican illegal aliens. Most New York City Hispanics are Puerto Ricans and they entered the country legally.