Continuity mistake: When Carl lets his dog out of the bag, in the close-up there's a shadow on Rod Steiger's boot, and a shadow of something or someone standing between him and the camera: both are gone in the following shot, when the dog runs across the lawn (and 'knocks aside' the camera). (00:08:20)
Visible crew/equipment: When Neil and Brenda are in the row boat, the bulge of the mic transmitter is visible at Brenda's lower back. (00:43:45)
Continuity mistake: When the Senior Civil Servant is reading Dowding's letter there is a knock at his door. In the next frame the Civil Servant has removed his glasses, appears more leaned back in his chair, and the position of the letter/page has also changed. (00:06:00)