On the Missing Persons card, Mary Anne Matthews is spelled with a "E" in Anne. It is also spelled this way in the credits. However, on the thank you card to Tom Welles from Mary Anne's mother at the end, the girl's name is spelled without an "E" by the mother.
When Dino says to Machine to hold down Tom Welles in the storage, Machine takes at the same time a knife in his (left) hand, but in the following scene, when Tom resists and shouts at Dino, we see once again Machine taking a knife from the table, in order to threaten Tom again.
When Tom Welles first meets Janet Mathews, he is looking at pictures of Mary Anne when he comes across a young picture of Janet. During the close up shots of the photographs, the picture behind the photo of Janet shows Mary Anne in a white shirt and green dress, while in the expanded shot of Janet and Tom, the photo shows Mary Anne in a blue shirt.
During the fight between Welles and Machine, towards the end of the film, they fall through the window into the cemetery. The way Machine holds his knife changes between the shot where he slips off the roof, and the next shot where he heavily lands on the ground.
The car Tom leaves the "studio" in when running from Eddie and the one he arrives at the cabin in are not the same car. The first car has caps over the lug nuts of the alloy wheels and the one at the cabin has the lug nuts exposed and the wheels are a different style.
In the warehouse, Longdale makes Poole kick his gun under the car, and this is the gun that he is reaching for. Some believe that Poole is trying to grab Longdale's gun, but he is really looking for his own.