Before Midnight focuses on the complexities of a long-term heterosexual relationship between its two main characters, Jesse and Céline. The narrative does not include identifiable LGBTQ+ characters or themes. The film's exploration of love, aging, and commitment is presented through the lens of this central couple and their interactions with a small supporting cast.

Before Midnight does not feature any identifiable transsexual characters or themes. The film's narrative centers entirely on the long-term relationship and personal reflections of its two main heterosexual protagonists, Jesse and Céline. The story explores universal themes of love, commitment, and the passage of time through their extensive dialogue and interactions.

The movie does not contain any action or adventure elements.

The film continues the narrative of its established protagonists, Jesse and Céline, who maintain their original genders as portrayed by the same actors across the film series. No characters previously established as one gender are portrayed as a different gender in this installment.

The film features the original actors portraying the established characters from previous installments. No characters who were canonically or widely established as one race are portrayed on screen as a different race.