When Mason is cross-examining Lois Langley, he refers to her "seeming disinterest in Consolidated Industries". However, the company is actually Hayden Electronics Research Company, as is shown on the sign outside the company when Lois and Thelma Frazer are leaving about ten minutes in.
During the initial courtroom scene at about 33:26 Della is wearing an outfit with a brooch on her left shoulder. At about 34:50, during the same courtroom scene, she's shown wearing a patterned sweater that she wears in several scenes the following day. Later, at about 35:16 (again same courtroom scene), she's back in the outfit with the brooch on the left shoulder. The one shot from the following day was put into the scene from the day before.
Early on, Thelma's friend is watching her kiss her boyfriend in his office, from the backseat of a car. Her view would indicate that his office is on the ground or maybe second floor, but the view from inside puts the office at least 4 or 5 floors up.
On the front page of the newspaper, "James Frazer's" photo is backwards. Throughout the show, he parted his hair on his left side; the photo shows otherwise.