Factual error: Passiflora Incarnata doesn't cause the symptoms described in the film. There was one remote incident where some of the symptoms (nausea) occurred but it can only happen if ingested which did not happen in this movie.
Continuity mistake: During the chat in the opening credits, Winona Ryder's right hand keeps changing position even when the flow of the conversation is continuous and there's absolutely no room for changes in between shots. When they talk about the crossbow case she even goes from holding a forkful of food, to a glass of wine. (00:02:00)