During the party scene, a couple of attendees discuss a "new preacher who is supposed to jump start the movement". One says that his name is "Michael" but the other corrects him and says that he "goes by Martin now". This is a reference to Martin Luther King. But in the summer of 1955, when the scene takes place, King was just a minister. He would only achieve widespread fame with the Montgomery Bus Boycott which began in the winter of 1955. It's highly unlikely that a bunch of people in Chicago would know of him, or think of him as being important to the Civil Rights movement. They certainly wouldn't know relatively obscure elements of his biography.
While talking about a "new preacher", one partygoer says that his name is "Michael" and another corrects him saying "He goes by Martin now". This is a reference to Martin Luther King. King was born Michael King, named after his father. However, after a trip to Europe, the elder King changed their names to Martin Luther in order to honor the founder of Protestantism. However, this name change occurred when King was just five years old. While friends sometimes called him "Mike", he was always know as Martin in his professional and public life. It's highly unlikely that someone in Chicago would know this obscure element of his life story, particularly in the summer of 1955, several months before King would achieve national fame with the Montgomery Bush Boycott.
During the Ouija board scene it is clear in the closeups that the fingers on the planchette are pressing down hard (when they should only be very lightly touching) and pushing it around the board.
When Leti breaks the glass of her white supremacist neighbors' cars, the glass instantly fractures into tiny, relatively safe shards, revealing that it is modern tempered glass.
No cars in 1955 had tempered windshields. In fact, the "safety" windshields of the time were designed to stay in one piece so that if a person were ejected through the windshield during an accident, the windshield would be knocked out rather than the person going through the windshield and suffering severe cutting injuries from the windshield breaking.
If the scene had been filmed with the glass that was available at the time, Leti would have had a much harder time breaking out the glass, and it would have broken into very large, potentially dangerous shards that may have injured her severely.
No cars in 1955 had tempered windshields. In fact, the "safety" windshields of the time were designed to stay in one piece so that if a person were ejected through the windshield during an accident, the windshield would be knocked out rather than the person going through the windshield and suffering severe cutting injuries from the windshield breaking.
If the scene had been filmed with the glass that was available at the time, Leti would have had a much harder time breaking out the glass, and it would have broken into very large, potentially dangerous shards that may have injured her severely.
A partygoer says that Martin Luther King, "married a colored girl last year". The scene takes place in 1955, but King married Coretta Scott in 1953.
In order to intimidate the Leti and the other African American "pioneers", a group of white men park cars outside and place bricks on the horns to keep them blaring day and night. This would not be a very effective method of chasing them out. As shown during the party, the doors and windows of the house are thick enough that the horns are essentially inaudible from inside the house. But even if the thugs did not know this, they would have to know that they would also be subjecting all the white neighbors to the same constant blaring of the horns.