Miscellaneous: When Lucy wakes up in the LA morgue, there is a scene showing she no longer casts a reflection. A minute later Lucy heads outside and you can clearly see a reflection of her in the doors glass and the shiny marble on the building.
Continuity: When Sadie is thrown on the bed by Bishop the bed is covered by a green duvet. In the next shot when they pin her to the bed it is covered with black plastic.
Continuity: When the detective is first shown placing photographs on his wall, there's already a picture of Harrison's bloody wheelchair wheel at the top. However, that crime scene is not discovered until several minutes later.
Revealing mistakes: After Sadie has sent Franny away she leans against the door. Her reflection is clearly visible in the glass, despite the fact that her lack of a reflection (due to being a vampire) is an important point in the movie.
Continuity: When Sadie stops to pick up the hitchhiker her vehicle's left tail light is burned out, yet minutes later when she turns off the main road it is working.
Continuity: When the detective is talking to Sadie after zipping up her jeans, the blade on her necklace is visible and clearly sitting to one side of her neck. In the next shot of her, it is hidden, and in the following shot it is visible again.
Continuity: Just before Sadie stabs Preacher in the heart, there is already blood down his shirt, then in the next shot it is white, then in the next it is bloody again
Errors made by characters (possibly deliberate errors by the filmmakers): When Det. Rawlins is in the hotel with Sadie, he remarks about her fast regeneration process after her back heals almost immediately from being shot. Later, when he lifts her off the meat hook to save her, she still has her foot injury from the stabbing by Poe sometime earlier.