The jacket Mark wears when locked in the study is not the same as the one he wears when he emerges on the porch (a scene explaining this was deleted).
When the camper van starts to tip, the shot changes to a wider view of the road, and the dummy is suddenly gone.
The same shot of a Chevrolet Caprice sliding into a blue car, and then a Ford LTD into those is used twice in the freeway wreck scene, from different angles.
The final wide shot of the freeway wreck has all of the vehicles in positions that are completely different to how they ended up in close-ups of the crashes.
The long view of the Evans' home shows no cliffs like the one where Susan goes to meditate, and where the final scene takes place.
In the highway wreck scene, several of the car windows blow out before they are actually hit.
Close-up shot of the Caprice station wagon hitting the snow mobile trailer in the freeway wreck scene clearly shows a completely empty road beyond, even though in every other shot there are multiple vehicles approaching and crashing.
During the crash scene, the rear window breaks out of a blue station wagon moments before it is actually hit.
When Henry pushes Susan off the ridge, the cable by which she slides down and which she hangs on is clearly visible.
After a leashless dog chases the kids on the bridge, it is shown barking behind a closed gate. For a brief moment a leash can be seen which reveals that the dog is tied up.
The dog on the bridge barks but the sound doesn't match it's mouth.
When Henry and Mark are climbing the tree at the start of the film, a crew member can be seen, dressed all in black, helping Mark on to the platform.
After Henry talks with Dr. Davenport, he and Mark talk in the tree-house. When Mark is sliding down the fire-hose, he stops to listen to Henry's threat and you can see Mark's safety line under his hand next to the fire-hose.
When they first fire the crossbow at the cat, and the bolt hits the tree, there is a obvious wire that the bolt traveled on sticking out the head of the bolt.