CW's birthmark is not a makeup effect. Actress Cassandra Naud was born with a large nevus under her right eye.
The voice-overs of Madison narrating after the title sequence were created with an actual AI voice creator, no actual recordings of Emily Tennant were used.
In a scene where CW takes Madison back to her place she has a copy of Mark Twain's The Innocents Abroad. One recurring theme in Twain's book is how he finds himself bored and even angered by places where history and culture is exploited for profit.