All these descriptions suggest that the Ghost entered through one of the doors, crossed the stage, and departed at another door.
When Hamlet awaits the Ghost, Horatio is the first to see it.
Look my lord, it comes.
[I, iv, 38]
Hamlet addresses the Ghost, urging it to answer. During this time there is opportunity for the Ghost to cross to the opposite door, then beckon to Hamlet to follow. Hamlet follows the Ghost through the door and five lines later Horatio and Marcellus follow them. Immediately the Ghost, trailed by Hamlet, enters through the door that he first used.
The final exit of the Ghost, according to Lawrence, is through the trap. The fact that the Ghost cries from the “cellarage” makes this suggestion convincing. It must be observed, though, that the Ghost does not speak until fifty-seven lines after he exits, or nearly three minutes later. Furthermore, John C. Adams has shown that the use of the main trap is usually accompanied by thunder to cover the sound of the trap mechanism. If this were the practice, the exit through the trap is unlikely.
The last of the ghost scenes in Hamlet, that in the Queen’s closet, is reminiscent of the other scenes. The Ghost enters, presumably through the stage door, chides his “tardy son” and departs. Endeavoring to convince Gertrude of his sanity, Hamlet describes the departure.
Why, look you there! Look how it steals away!
My father, in his habit as he liv’d!