Continuity mistake: When Vince leaves the freezer and is making his way onto the elevator, he is carrying a Baretta model pistol. When he shoots as the elevator doors are closing the camera cuts to a Glock model pistol, then back to the Baretta again. When the elevator reaches the upper level, the woman picks up the remains of the backfired pistol and it is back to the Glock. (01:21:15 - 01:24:30)
Continuity mistake: After Nicole smokes her last cigarette (literally), and starts to decompose, the blood stain on her chest changes in size. At first, it is pretty big and on only one side. In the next shot that she is in, the blood stain separated causing a small stain on one side of her chest, and a slightly larger stain on the other. (01:08:40)
Chosen answer: Vince explains this. The letters spell out CROATOAN. There was an English colony on Roanoake Island, of which the entire population mysteriously disappeared, giving no trace of what had happened, barring the letters CROATOAN carved on to a tree.