Donna enters Stephen's office holding some papers at waist height (elbows bent), but in the shot from behind, her right arm is straight down. The following shot (from the front) again shows her elbow bent.
A photo of Stephen's rugby team shows 12 players in it. A rugby team may have 7, 13 or 15 players but in no case 12.
In the opening scene between Harvey and Stephen, the film is reversed, as evidenced by the fact that Gabriel Macht's moles on his forehead, which are on the left side of his face, are, for a moment, on the right side of his face.
When Harold is on the witness stand Nigel asks him "Who was your supervisor?" Harold responds, "That man, Louis Litt", and points at Louis. Nigel then says, "Let the record show that Mr. Gunderson indicated Mr. Litt." This statement would be unnecessary as Harold called out Louis by name, so it is on the record. Had he just pointed at Louis and said something like "Him", then Nigel's statement would be needed as the record is written and one wouldn't be able to tell who "Him" was.
During a discussion there is a short take of Harvey Spector in mirror image with the moles on the right side on his face.