One of Barry's acting classmates says "You're gonna be an amazing MacBeth... uh, Scottish... king." This is a reference to an old superstition in the theatre world which says that the title of Shakespeare's "MacBeth" brings bad luck, and that it should only be referred to as "the Scottish play".
Gene Cousineau says he is 47 years old, where in real life Henry Winkler is 73 years old.
Sally wants to do the "Tomorrow and tomorrow and tomorrow" soliloquy from Macbeth Act 5, Scene 5; a short piece with no weird cadences or usages. But the required soul-dead, nihilistic, grieving surrender to despair is very, very hard to do well. Bad actors generally over-emote; good actors understand that here Macbeth is already dead inside.
Sally's emotions on the other hand are the exact opposite after getting the nod from Cousineau, symbolized by the "Fight Song" she plays when sitting in the car.
One of Taylor's surprise mercenary extras is proud of his Bushmaster gun. The Bushmaster is in the AR15 family, a non-fully automatic civilian version of a military combat weapon.