Revealing mistake: Most of the blood seen in this film is too light to be considered real human blood. In the public trap it is practically pink. The reason for this is the 3D effect. When watched in 3D, it looks more like normal blood. But in normal viewing, it does look too light. (00:06:00)
Revealing mistake: During Jill's dream where she is killed by the "Death-Kart", watch closely. During at least two shots, you can see wires near the wheels that are pulling the cart, revealing it isn't self-propelled as depicted. (They are visible in the third shot of it moving forward, where the camera moves upwards and tilts down, and in the sixth shot of the moving cart, where the camera is looking down). (00:17:40)
Revealing mistake: When Dr. Gordon says that everyone is grateful to Bobby, there is an over-the-shoulder camera angle. In this angle it is clear that Dr. Gordon is not talking. Yet his voice continues. (00:25:25)
Revealing mistake: When Bobby's wife is dragged to her knees by the chain, you can make out the shape of her knee pads under her trousers. (00:41:10)
Revealing mistake: When Gibson is watching the Hoffman DVD for the second time, the timer bar at the bottom of the video isn't moving. (00:43:45)
Revealing mistake: When Gibson is explaining how Hoffman saved his life, in the flashback he closes his eyes and braces for the bottle attack before it arrives. (00:55:20)
Revealing mistake: If you look very carefully when Gibson is machine gunned down, you can see the blood packs in his jacket. Slow-Mo may help but is not essential. (01:07:15)
Revealing mistake: When the door slams shut on the SWAT team, watch the wall. It wobbles. (01:09:10)
Revealing mistake: Just before Hoffman knocks Jill out, there is no blood on her head or the table. As he grabs her head blood appears on her head just before he smashes it on to the table. (01:14:40)
Revealing mistake: Spoiler: Right at the end when Dr. Gordon looks at his severed foot from SAW, note the blood pattern on the tiled floor. The blood seems to go at right angles around 2 tiles. Blood should just spread out, not take the pattern on the tiles. (01:21:15)
Answer: Dr. Gordon from the 1st movie, and Ryan and Brad from the trap in the beginning of this movie.
derrick g