At about 8 minutes in, Gaetano empties his revolver at the door, firing eight times (count 'em!). With few exceptions, revolvers hold only six cartridges, and when the door opens, there are six holes in the door.
Loy tells Gaetano that his henchman, Omie, apparently has one of the best right crosses in boxing, but when the bell rings for him to inflict some damage on Gaetano, Omie takes a very clear southpaw stance, meaning that his crosses would always come from the left.
When talking to Oraetta, Dr. Harvard uses the modern term "human resources" rather than "personnel department" as would have been the case in 1950.
When Naneeda realizes where Antoon is going, she makes the sign of the cross. However, she does it backwards for an Italian Roman Catholic, touching her right shoulder before her left. While correct in an Eastern church, it is incorrect for a 20th century Roman Catholic.