Continuity mistake: When Amanda and Daniel entered the bathroom from 'Saw', Adam's body is shown with his right leg shackled. However, in 'Saw' and in Adam's death flashback in 'Saw III', his left leg is shackled. (01:14:10)
Continuity mistake: When Seth has been sliced by the blade, he spits blood that goes all over his face. It then cuts to Hoffman looking at him, then back to Seth, and now the blood on his face has gone. This happens three or four times. (00:05:10)
Continuity mistake: When Chris talks to the cop and then the cop gets shot with an arrow, Chris runs into the truck and the man shoots another arrow. So altogether he shoots two times. The first one is in the cop's eye, so how come when he shoots the second through the truck window, there are now two arrows there, not one. He only fired two arrows and we see three. (01:04:20)
Continuity mistake: At the start, Robert Neville drives into some yellow poles, only to drive into them again in the following shot.
Continuity mistake: When Bucky jumps on the hood of the bus to get back in, the Creeper flies from in front of the moon towards the bus causing all the kids to run away. Bucky can still be seen staying put on the hood when they run - however in the next shot of all the kids running you see him at the front of the pack which would have not been possible given that he didn't run right away.
Continuity mistake: When Jamie Lee Curtis is teaching a class, just prior to the class trip, a shot over her shoulder shows on the blackboard 'W.B. Yates'. It should be spelled 'Yeats'. In a shot a few seconds later the spelling has been corrected.
Continuity mistake: When the girl shoots herself her body is still sitting upright in the backseat, but when the van hits a bump in the road and the body falls onto its side. When the van stops in the next shot the body is sitting back up again without anyone moving it.
Continuity mistake: Just before the giant tarantula attacks the house where heroine Mara Corday is studying, you can see several book on the library table at the big picture window. The largest book on the table keeps shifting positions in several scenes.
Continuity mistake: When Trent and Bree are having sex, the ceiling fan is on then off.
Continuity mistake: When Fin stops near the school bus, the bus number changes from "278146" to "278245" during the rescue of the kids.
Continuity mistake: When Amber and Jonesy get an arrow through the head, the cannibal was on Jonesy's side, so the tip should have gone through Amber's head, not Jonesy's.
Continuity mistake: A blond boy in a light brown shirt is attacked by a crow and goes from having no blood on his neck to having a lot of blood smeared on his neck between shots. (01:14:10)
Continuity mistake: When the car door is ripped off by the cow, it shows the truck with the door intact.
Continuity mistake: In the scene where the Nemesis kills the 13 S.T.A.R.S members, after it blows up the sniper on the roof an additional S.T.A.R.S member can be seen outside the building on the right who wasn't there earlier. He then disappears shortly afterwards.
Continuity mistake: When chasing Jamie in the woods, Mikey's headlights go from normal chevy headlights to off-road high beams.
Continuity mistake: When Sister Irene's habit is ripped at the back, you can see a bra strap on her left shoulder which disappears when she is seen at the front and when the camera is closer to her back (when she has the pentagram carved into her).
Continuity mistake: In the scene where Jonathan picks up the scarab, it breaks open and the beetle inside starts to crawl under his skin. We see Brendan Fraser tear Jonathan's shirt and cut the beetle out of him. However, in the very next scene, we see Jonathan walking into the temple, his shirt is intact and there is no blood to be seen. (01:37:05 - 01:38:30)
Continuity mistake: When Ghostface is trying to kill Tatum in the garage, she tries to go through the doggie door. From the outside shot, she is out of the door from her arms and up. From the inside shot, she is out of the door from her hips and up. (01:04:20)
Continuity mistake: When Mommie is cutting Christina's hair it keeps on changing from long to short several times.
Continuity mistake: At the start of the film, the dog is seen going from room to room looking for food. Just before he goes into Dana's room, someone can be seen through the crack in the door, moving from left to right.