The lyrics to the song that Fleance sings at Macbeth's banquet for Duncan at Inverness are taken from the poem "Merciles Beautè" by Geoffrey Chaucer. In the context of the film this extraneously inserted song is itself an anachronism, as Chaucer lived in the fourteenth century and Shakespeare's "Macbeth" historically takes place in the eleventh century.
When Macbeth dines after Banquo's death, time freezes for 5-10 seconds as Macbeth sees Banquo's ghost sitting at the table. This is achieved by the other actors freezing in place until Macbeth drops his chalice. During the time freeze, a man sitting at the table and facing the camera blinks his eyes.