When Curtis has his seizure, the time on the nightstand clock changes from 2:23 to 2:30, and then back to 2:28 (which then changes to 2:29 on camera).
(at around 1 min) When Curtis is having a seizure on one scene the pillow is next to him with a big blood stain close to the clock. In the next scene when he sits up, the pillow is behind him towards the middle. This happens twice during that sequence.
When Samantha is trying to sell a pillow to the woman in the market scene. Some extras can be seen from both sides of the market at the same time.
Curtis and Shannon live in LaGrange, Ohio. However, Curtis's truck has Erie County tags on its license plates. LaGrange is in Lorain County, one county to the east.