Like all of Shakespeare's plays, "Macbeth" is filled with theatricality and an awareness of its own status as a drama.
You might turn first to the way that Macbeth and Lady Macbeth will look like "th'innocent flower but be the serpent under't", or her later mantra that "false face must hide what the false heart doth know". What better encapsulation could there be of the role of an actor - "putting on" emotions and expressions in order to deceive an audience?
Remember too that critics disagree hugely about Lady Macbeth's "faint" just after everyone has discovered the murdered Duncan: some people think she puts it on to distract attention from Macbeth (whose rhetoric is, to be fair, slightly less than impressive).
You might want to think about the apparitions which vanish and appear to Macbeth in the witches scene, and the dagger ("air-drawn") which appears before he murders Duncan - and, of course, the ghost of Banquo. Puck, in "A Midsummer Night's Dream" describes actors as "shadows", and "The Tempest" has them vanish into "thin air". Acted characters are transitory - can vanish as soon as the performance finishes.
And lastly, don't forget Macbeth's own "tomorrow and tomorrow" speech, which compares life to a "poor player" upon a stage: a typically meta-theatrical moment which reminds us that Macbeth is simply a character played by an actor.