Continuity mistake: When Rennie gets up and walks over to the closet, you can see some items on the side, such as a decorated silk cloth, a bag etc. When Jason then looks through the porthole into Rennie's room, the position of all the items are different. (00:21:35)
Visible crew/equipment: As Rachel runs to the airplane through the line of passengers, on her way back to the house from her parents in Chicago, you can see lighting equipment reflected in the glass window, before it cuts away. (01:11:00)
Continuity mistake: When Tim gets stabbed, the killer's silhouette shows that he's holding his knife overhand. When he stabs Tim, he's holding the knife underhand.
Continuity mistake: When Redferne finds the page of the Grand Grimoire, he is holding it with his right hand. In the next shot, he is holding it with his left hand. (00:52:17)
Continuity mistake: When Fuller falls to his death, the mannequin used as his stand-in gets decapitated on its way down. It even makes a loud noise. When Fuller lands, however, his head is still on his shoulders.