Continuity mistake: When Sam is in the bathroom holding up two sample paint chips, in the first shot she's holding up the yellow in her left hand and the blue in her right hand, but in the next shot they've switched and are in the opposite hands, just as Jay arrives with the coffee.
Continuity mistake: At the foot of the stairs, Higgentoot is facing away from the group, and his hands are by his sides. As he turns, they're suddenly behind his back.
Continuity mistake: Pete's arrow is sometimes straight and sometimes crooked. Since it's the manner in which he died, it should be consistent.