At 00:50 the picture on Bruce Granger's desk sits stage right facing Granger's chair. At 01:45, without seeming human intervention, the picture has rotated 180 degrees and drifted to stage left so as to face the camera revealing the image of Sybil Granger.
In Mrs. Granger's first scene with Perry, a bug can be seen crawling on the camera lens.
In the opening scene, Perry's binocular vision changes from a wide view of the backyard to a close-up of the woman and then the couple. There's no zoom lever on the binoculars, so there's no way the view could have changed.
When Perry fires a blank at the white fabric without leaving a wadding hole, no one in the courtroom explicitly says that has happened. In a real hearing, the judge would have told the court reporter to record the results of the test firing for the transcript.