Continuity mistake: When Dr. Heywood is talking to his daughter, her hands shift between the first full shot on the screen and the shot over Heywood's shoulder.
Continuity mistake: For most of the sequence during which the Orion space shuttle closes in to dock with Space Station One, we see the space station rotating counterclockwise, as viewed from the side the Orion is approaching. But the first two times we see the station (immediately before and immediately after the scene in which Floyd's pen floats free aboard the Orion), it is rotating clockwise. It is also apparently rotating clockwise in the shot from inside the station, looking out at the approaching Orion. The stars in this shot are turning clockwise, implying that the station is moving anti-clockwise, hence must be rotating clockwise when observed from the Orion.
Continuity mistake: When Dr. Floyd is talking to Dr. Smyslov and his colleagues, Dr. Smyslov's hair moves several times between shots.
Continuity mistake: In the white hotel, the first transition shows a middle-aged Dave with graying hair. In the shot over middle-aged Dave's shoulder to show that the pod is gone, he has dark hair again.
Continuity mistake: When we see the outside of the cave where the apes are sleeping for the first time it's at sunset. We can see the sun and cloud behind the cave as if it is just sitting in a rock face with nothing behind it, but in the next shot when it's daytime suddenly there is a background of rocks and mountains behind the cave.
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.
Answer: As author Arthur C. Clarke explained it, the first Monolith (the one seen at the beginning of the film and then buried on the Moon) was a space probe from an incomprehensibly more advanced alien intelligence that resided inside a star elsewhere in the cosmos. The Monolith's objective was to seek out lifeforms that had potential and "tweak" their neural evolution, causing them to evolve toward intelligence. In the case of Mankind on Earth, once the modification was made, the Monolith probe retreated to the Moon and waited 4 million years for Mankind to reach it. When Mankind reached the Moon, the Monolith sent a signal to the next phase of the experiment, which was another Monolith in orbit of Jupiter. When Mankind reached the Jupiter Monolith in a matter of months, the Monolith acted as an interdimensional portal to the other side of the universe, transporting the evolved human specimen to its creator (that resided within a star). The creator intelligence found the specimen (Dave Bowman) to be of acceptable quality and rapidly evolved him to the next level, a Star Child. The Star Child is a "godly" evolution of Mankind. The Star Child chooses to instantaneously return to its home planet (Earth), where it stops a nuclear war.
Charles Austin Miller