In the original performances of Shakespeare's plays, and many since, financial and other constraints led to the same actors playing several minor parts. Goodnight Desdemona (Good Morning Juliet) makes use of this convention to comic and dramatic effect, having eighteen parts normally played (as in the cast list attached below) by six actors. Only the actress playing Constance, the protagonist, does not play any other parts.

The effects achieved by the way the roles are apportioned can be comic, as when the actor playing the suave and manipulative Professor Claude Night reappears as Juliet's Nurse. This is typical of the play's blurring of gender differences. However, a more sinister effect occurs when the same actor also plays Othello. The Nurse shows Professor Night's ludicrous side, while Othello hints at how dangerous he can be.

The play also makes tragic couples comic, or otherwise alters their status, partly through having the same two actors play two sets of couples. Julie and her boyfriend thus reflect the relationship of Juliet and Romeo. Again, while the same actor plays Professor Night and Othello, the actress playing Desdemona also doubles up as Ramona, the Professor's much younger girlfriend. This suggests parallels in their relationships, with worrying implications for Ramona. Aside from these specific parallels, the multiple roles of the actors add to the sense of chaos in the mixture of life and drama that creates much of the play's comic energy.