Visible crew/equipment: When Olivia is saying goodbye to the children, when she leans in to talk to Luke if you look at her left hip you can see a microphone pack sticking out. (00:22:02)
Visible crew/equipment: While Theo explores the basement of the Dunlaps, the family of one of her patients, a boom mic can be briefly be seen in the upper right corner. (00:19:31)
Other mistake: While working in the basement, the young Hugh Crain gets his right hand sliced badly by a fan. When the story next jumps forward to the present time, the first thing we see is Hugh grabbing a handful of dirt with the same hand and there is barely a scar on it.
Trivia: In the original novel, the characters Eleanor, Theo and Luke were not siblings. In addition, the characters Steven and Shirley didn't exist in the original novel. This series - a re-imagining of the novel - made the main characters into siblings and added Steven and Shirley to broaden the cast a bit. Shirley is named after Shirley Jackson, who wrote the novel.