In theater circles, Macbeth is considered to be an unlucky play. Saying the play's name aloud is considered bad luck – that's why it's often referred to as "the Scottish play."
At about half the length of Hamlet, Macbeth is one of Shakespeare's shortest plays.
Some scholars believe that the scenes involving Hecate were added in by later theater writers, not Shakespeare himself. They seemed a good opportunity for the song and dance routines that livened up the otherwise dark play. (Source: Kiefer, Frederick. Shakespeare's Visual Theatre: Staging the Personified Characters. Cambridge, England; New York: Cambridge University Press, 2003. 101.)
In 1936, the Federal Theater Project sponsored a highly successful version of Macbeth at the Lafayette Theater in Harlem. Featuring an all Black cast and set in post-colonial Haiti, the production was known for spectacular direction and the imposing sounds of drums. It was the first stage production of a young man in his early twenties named Orson Welles. (Source)
The trio of weird sisters represents a literary convention that was popular in Shakespeare's day: the three Fates as represented by the maiden, the matron, and the hag, or Past, Present, and Future respectively. (Source: Ewing, Thor. Gods and Worshippers in the Viking and Germanic World. Stroud Gloucestershire, England: The History Press Ltd., 2008.)
Orson Welles's 1948 film of Macbeth was not considered a critical success in the United States. (Source)