- Executive Meddling: About a hundred years after Shakespeare died, an English theatre impresario (probably Colley Cibber) added an extra "witches" scene to Act III which was later assumed to have been part of the original play. (After the witches' "double, double, toil and trouble" speech, Hecate and three other witches show up randomly, sing a song called "Black Spirits", and vanish). This is never mentioned again. Most versions of the play produced before about 1970 include this scene; most since leave it out.
- Hey, It's That Guy!: The RSC production filmed for television in 1979 is known universally as the nerd-tastic production. Why? Because...
- No Budget: The play can be thrown together on the cheap. That's part of the reason it's so dangerous. The easiest way to conjure up that spooky Highland atmosphere is with darkness, and lots of it. Now just throw in lots of daggers and swords, and long, heavy cloaks that everyone can trip on and, yes, you can see the problem.
- Also the Roman Polanski version: Macbeth was played by Jon Finch who was first choice for Doyle in The Professionals. Banquo was played by Martin Shaw who DID play Doyle!
- Cultural Translation: A 1970 Zulu-language adaptation by South African playwright Welcome Msomi, called uMabatha, adapts the play into Zulu tribal culture of the early 19th century (around the reign of the famous King Shaka). Actor and theater critic Peter Ustinov remarked that until reading uMabatha, he did not understand Macbeth. Nelson Mandela remarked on the similarities between Macbeth and King Shaka.
- The 8th among the royal descendants of Banquo who appear in the witchcraft induced vision in Act 4 is supposed to be King James I of England, who was believed to be 8 generations removed from the real life Banquo. Somewhat ironically, the current British royal house is actually descended from the Thanes of Glamis, the old fief belonging to Macbeth himself in the play, since the Queen Mum, the mother of the current Queen Elizabeth II, is of a Scottish noble family who has been the real Thanes of Glamis since 14th century and spent her childhood there.