Continuity mistake: In the scene where HAL is reading the lips of Bowman and Poole through a pod window, while they are in the pod discussing his possible disconnection, they are shown to be directly facing each other, keeping their heads perfectly still, while HAL looks back and forth from mouth to mouth. In the previous scene, the two men were not conversing in this unusual manner.
Continuity mistake: In several scenes, we are given HAL's visual perspective as if seeing through his lens. This is done with an overlayed image of the lens on whatever area is in sight of the lens. As Dave is entering HAL's memory circuit room (red lighting), one shot again suggests we are again seeing what HAL sees, but there is no HAL lens located and oriented to provide the angle we see. A lens would need to be mounted on the narrow wall directly opposite the circular doorway, yet HAL's lens in this room is mounted on the 'ceiling'. (01:51:25)
Continuity mistake: In a sequence in the cockpit of the space ship approaching docking, the shot shows the two pilots and 3 monitor screens between them. The right-hand screen changes from a data display to a blank showing only the letters "GDE" (possibly "GOE"). The next shot is a close-up of the three monitors, and the right-hand one now shows its earlier data display. The other two do not show this behaviour. (00:25:00)
Continuity mistake: During Heywood's meeting with Elena and Dr Smyslov, he is introduced to their colleagues, including Dr Kalinan who is the women in the olive dress/suit. When they shake hands her coat is folded neatly over her seat, but before she sits down again with the camera now facing Heywood, the coat disappears. In an earlier shot prior to the introduction, the majority of Kalinan's coat is off the seat and when she stood the first time it probably fell, suggesting the handshake sequence was re-filmed after the actual meeting. (00:28:45)